Benzimidazo[1,2-a]benzimidazole derivatives for electronic applications

ABSTRACT

A compound of the general formula (I), 
                         
a process for the production of the compound and its use in electronic devices, especially electroluminescent devices. Improved efficiency, stability, manufacturability, or spectral characteristics of electroluminescent devices are provided when the compound of formula I is used as host material for phosphorescent emitters in electroluminescent devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/453,591, filed Mar. 8, 2017, now allowed, which is acontinuation of U.S. patent application Ser. No. 14/413,736, filed Jan.9, 2015, now U.S. Pat. No. 9,620,724, which is the U.S. National StageApplication filed under 35 U.S.C. § 371 of International PatentApplication No. PCT/EP2013/064395, filed Jul. 8, 2013, which claimspriority to U.S. Provisional Patent Application Nos. 61/669,677, filedJul. 10, 2012, and 61/702,267, filed Sep. 18, 2012, and European PatentApplication Nos. 12175635.7, filed Jul. 10, 2012, and 12184786.7, filedSep. 18, 2012, all of which applications are hereby incorporated byreference in their entireties.

The present invention relates to compounds of formula I, a process fortheir production and their use in electronic devices, especiallyelectroluminescent devices. When used as hole transport material inelectroluminescent devices, the compounds of formula I may provideimproved efficiency, stability, manufacturability, or spectralcharacteristics of electroluminescent devices.

Khan, Misbahul Ain; Ribeiro, Vera Lucia Teixeira, Pakistan Journal ofScientific and Industrial Research 43 (2000) 168-170 describes thesynthesis of benzimidazo[1,2-a]benzimadozoles

(R═H, Me, Et) by trialkyl phosphite-induced deoxygenation andthermolysis of 1-(o-nitrophenyl)- and 1-(o-azidophenyl)benzimidazoles.

Pedro Molina et al. Tetrahedron (1994) 10029-10036 reports that azaWittig-type reaction of bis(iminophosphoranes), derived frombis(2-aminophenyl)amine with two equivalents of isocyanate directlyprovided benzimidazo[1,2,a]benzimidazole derivatives.

R=isopropyl and R′=ethyl)

Kolesnikova, I. V.; Zhurnal Organicheskoi Khimii 25 (1989) 1689-95describes the synthesis of 5H-benzimidazo[1,2-a]benzimidazole1,2,3,4,7,8,9,10-octafluoro-5-(2,3,4,5,6-pentafluorophenyl).

Achour, Reddouane; Zniber, Rachid, Bulletin des Societes ChimiquesBelges 96 (1987) 787-92 describes the synthesis ofbenzimidazobenzimidazoles

(R═H, —CH(CH₃)₂) which were prepared from benzimidazolinone derivatives.

Hubert, Andre J.; Reimlinger, Hans, Chemische Berichte 103 (1970)2828-35 describes the synthesis of benzimidazobenzimidazoles

(R═H, CH₃,

JP2001160488 describes an electroluminescent element which has alight-emitting layer having a single-layer or multiple-layer organiccompound film between opposing anode and cathode, wherein at least onelayer of the organic compound film contains at least one kind ofcompounds indicated by formula

The following compounds are explicitly disclosed:

US20100244006 relates to an organic electroluminescent device whichincludes: a cathode; an anode; and at least one organic layer betweenthe cathode and the anode. The at least one organic layer includes alight emitting layer containing at least one light emitting material. Acompound represented by the following formula

is contained in the at least one organic layer. where n stands for aninteger of 2 or greater, L represents an n-valent linking group, and R¹,R², R³, and R⁴ each independently represents a hydrogen atom or asubstituent.

The compounds described in US20100244006 are preferably used in as hostin the light emitting layer.

represents an example of a compound disclosed in US20100244006.

KR1020110008784 relates to novel organic luminescent compounds offormula

and organic electroluminescence devices including the same.

US2005079387 relates to an imidazole ring containing compound of formulaAr₁—Ar₂—Ar₃, (blue luminescent host compound) and an organicelectroluminescence (EL) display device using the same.

Ar₂ is selected from the group consisting of

each of Ar₁ and Ar₃ is independently selected from

wherein X′ is O, or S.

US2005074632 relates to an imidazole ring containing compound of formula

and an organic electroluminescence (EL) display device using the same.In particular, the imidazole ring-containing compound may be used aloneor in combination with a dopant as a material for organic films such asan electroluminescent layer.

A is selected from the group consisting of

—N(R₁₃R₁₄), and

B is selected from the group consisting of

X is selected from the group consisting of —O—, —S—, —Se— and —NH—.

JP2007180147 relates to an organic electroluminescence element,sandwiched by an anode and a cathode and containing at least alight-emitting layer, which contains a compound represented by generalformula 1, 2, 3 or 4:

Ar₁-Ar₄=aromatic group or aromatic heterocyclic group; R₁-R₅═H orsubstituent; Z₁=residue required to form heterocyclic ring of 5 or 6members; L₁, L₂=bond or coupling group; and X₁-X₁₆=carbon or nitrogen. Anew ring can be formed in one portion of Ar₁ and Ar₂, and Ar₃ and Ar₄.

The following compounds are explicitly disclosed:

U.S. Pat. No. 6,551,723 relates to an organic electroluminescenceelement comprising a light-emitting layer or a plurality of organiccompound thin layers containing a light-emitting layer between a pair ofelectrodes, wherein at least one layer in the organicelectroluminescence element comprises at least one heterocyclic compoundrepresented by formula (I) to (VII):

R₁₁, R₁₂, R₁₃, R₂₁, R₂₂, R₃₁, R₃₂, R₄₁, R₄₂, R₅₁, R₆₁, and R₇₁ are eachindependently a hydrogen atom or substituent; Z₁, Z₂, Z₃, Z₄, Z₅, Z₆,and Z₇ are a group of atoms that are necessary for forming a 5- or6-member ring. The compounds represented by formula (I) to (VII) areparticularly added to a light-emitting layer and/or electroninjection/transporting layer. The following compounds are explicitlydisclosed:

WO2011160757 relates to an electronic device comprising an anode,cathode and at least one organic layer which contains a compound offormulae

wherein X may be a single bond and L may be a divalent group. Thefollowing 4H-Imidazo[1,2-a]imidazole compounds are explicitly disclosed:

X. Wang et al. Org. Lett. 14 (2012) 452-455 discloses a highly efficientcopper-catalyzed synthesis for compounds of formula

wherein compounds of formula

are reacted in the presence of copper acetate(Cu(OAc)₂)/PPh₃/1,10-phenathroline/sodium acetate and oxygen in m-xylene(1 atm) at elevated temperature [published on web: Dec. 29, 2011]. Amongothers the following compounds can be prepared by the describedsynthesis method:

WO2012/130709 relates to 4H-Imidazo[1,2-a]imidazoles,

such as, for example,

a process for their production and their use in electronic devices,especially electroluminescent devices.

WO2013/050401 describes 4H-imidazo[1,2-a]imidazoles of formula

wherein X⁶ is —N═ and X⁷ is —NR⁶—, or X⁷ is ═N— and X⁶ is —NR⁶—, R⁶ is agroup of formula

such as, for example,

a process for their production and their use in electronic devices,especially electroluminescent devices.

Notwithstanding these developments, there remains a need for organiclight emitting devices comprising new hole transport materials toprovide improved efficiency, stability, manufacturability, and/orspectral characteristics of electroluminescent devices.

Accordingly, it is an object of the present invention, with respect tothe aforementioned prior art, to provide further materials suitable foruse in OLEDs and further applications in organic electronics. Moreparticularly, it should be possible to provide hole transport materials,electron/exciton blocker materials and matrix materials for use inOLEDs. The materials should be suitable especially for OLEDs whichcomprise at least one phosphorescence emitter, especially at least onegreen emitter or at least one blue emitter. Furthermore, the materialsshould be suitable for providing OLEDs which ensure good efficiencies,good operative lifetimes and a high stability to thermal stress, and alow use and operating voltage of the OLEDs.

Certain 2,5-disubstituted benzimidazo[1,2-a]benzimidazole derivativesare found to be suitable for use in organo-electroluminescent devices.In particular, certain 2,5-disubstituted benzimidazo[1,2-a]benzimidazolederivatives are suitable hole transporting materials, or host materialsfor phosphorescent emitters with good efficiency and durability.

Said object has been solved by compounds of the formula

wherein

R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are independently of each other H, aC₁-C₂₅alkyl group, which can optionally be substituted by E and orinterupted by D; a C₆-C₂₄aryl group, which can optionally be substitutedby G, or a C₂-C₃₀heteroaryl group, which can optionally be substitutedby G;

X¹ is a group of formula —(A¹)_(o)-(A²)_(p)-(A³)_(q)-(A⁴)_(r)—R^(16′),

o is 0, or 1, p is 0, or 1, q is 0, or 1, r is 0, or 1,

A¹, A², A³ and A⁴ are independently of each other a C₆-C₂₄arylen group,which can optionally be substituted by G, or a C₂-C₃₀heteroarylen group,which can optionally be substituted by G; wherein

the groups A¹, A², A³ and A⁴ may be interrupted by one, or more groups—(SiR¹⁷R¹⁸)—;

X² is a group of formula —(A⁵)_(v)-(A⁶)_(s)-(A⁷)_(t)-(A⁸)_(u)—R¹⁵,—NR¹⁰R¹¹, or Si(R¹²)(R¹³)(R¹⁴),

v is 0, or 1, s is 0, or 1, t is 0, or 1, u is 0, or 1,

A⁵, A⁶, A⁷ and A⁸ are independently of each other a C₆-C₂₄arylen group,which can optionally be substituted by G, or a C₂-C₃₀heteroarylen group,which can optionally be substituted by G; wherein

the groups A⁵, A⁶, A⁷ and A⁸ may be interrupted by one, or more groups—(SiR¹⁷R¹⁸)—;

R¹⁰ and R¹¹ are independently of each other a C₆-C₂₄aryl group, whichcan optionally be substituted by G; or a C₂-C₃₀heteroaryl group, whichcan optionally be substituted by G; or

R¹⁰ and R¹¹ together with the nitrogen atom to which they are bondedform a heteroaromatic ring, or ring system;

R¹², R¹³ and R¹⁴ are independently of each other a C₁-C₂₅alkyl group,which can optionally be substituted by E and or interupted by D;C₆-C₂₄aryl group, which can optionally be substituted by G; or aC₂-C₃₀heteroaryl group, which can optionally be substituted by G;

R¹⁵ is a C₆-C₂₄aryl group, which can optionally be substituted by G; ora C₂-C₃₀heteroaryl group, which can optionally be substituted by G;

R^(16′) is a C₆-C₂₄aryl group, which can optionally be substituted by G;or a C₂-C₃₀heteroaryl group, which can optionally be substituted by G;

R¹⁷ and R¹⁸ are independently of each other a C₁-C₂₅alkyl group, or aC₆-C₂₄aryl group, which can optionally be substituted by one, or moreC₁-C₂₅alkyl groups; D is —CO—, —COO—, —S—, —SO—, —SO₂—, —O—, —NR⁶⁵—,—SiR⁷⁰R⁷¹—, —POR⁷²—, —CR⁶³═CR⁶⁴—, or —C≡C—,

E is —OR⁶⁹, —SR⁶⁹, —NR⁶⁵R⁶⁶, —COR⁶⁸, —COOR⁶⁷, —CONR⁶⁵R⁶⁶, —CN, orhalogen,

G is E, or a C₁-C₁₈alkyl group, a C₆-C₂₄aryl group, a C₆-C₂₄aryl group,which is substituted by F, C₁-C₁₈alkyl, or C₁-C₁₈alkyl which isinterrupted by O; a C₂-C₃₀heteroaryl group, or a C₂-C₃₀heteroaryl group,which is substituted by F, C₁-C₁₈alkyl, or C₁-C₁₈alkyl which isinterrupted by O;

R⁶³ and R⁶⁴ are independently of each other H, C₆-C₁₈aryl; C₆-C₁₈arylwhich is substituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; C₁-C₁₈alkyl; orC₁-C₁₈alkyl which is interrupted by —O—;

R⁶⁵ and R⁶⁶ are independently of each other a C₆-C₁₈aryl group; aC₆-C₁₈aryl which is substituted by C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; aC₁-C₁₈alkyl group; or a C₁-C₁₈alkyl group, which is interrupted by —O—;or

R⁶⁵ and R⁶⁶ together form a five or six membered ring,

R⁶⁷ is a C₆-C₁₈aryl group; a C₆-C₁₈aryl group, which is substituted byC₁-C₁₈alkyl, or C₁-C₁₈alkoxy; a C₁-C₁₈alkyl group; or a C₁-C₁₈alkylgroup, which is interrupted by —O—,

R⁶⁸ is H; a C₆-C₁₈aryl group; a C₆-C₁₈aryl group, which is substitutedby C₁-C₁₈alkyl, or C₁-C₁₈alkoxy; a C₁-C₁₈alkyl group; or a C₁-C₁₈alkylgroup, which is interrupted by —O—,

R⁶⁹ is a C₆-C₁₈aryl; a C₆-C₁₈aryl, which is substituted by C₁-C₁₈alkyl,or C₁-C₁₈alkoxy; a C₁-C₁₈alkyl group; or a C₁-C₁₈alkyl group, which isinterrupted by —O—,

R⁷⁰ and R⁷¹ are independently of each other a C₁-C₁₈alkyl group, aC₆-C₁₈aryl group, or a C₆-C₁₈aryl group, which is substituted byC₁-C₁₈alkyl, and

R⁷² is a C₁-C₁₈alkyl group, a C₆-C₁₈aryl group, or a C₆-C₁₈aryl group,which is substituted by C₁-C₁₈alkyl.

The compounds of the present invention may be used forelectrophotographic photoreceptors, photoelectric converters, organicsolar cells (organic photovoltaics), switching elements, such as organictransistors, for example, organic FETs and organic TFTs, organic lightemitting field effect transistors (OLEFETs), image sensors, dye lasersand electroluminescent devices, such as, for example, organiclight-emitting diodes (OLEDs).

Accordingly, a further subject of the present invention is directed toan electronic device, comprising a compound according to the presentinvention. The electronic device is preferably an electroluminescentdevice.

The compounds of formula I can in principal be used in any layer of anEL device, but are preferably used as host, hole transport and electronblocking material. Particularly, the compounds of formula I are used ashost material for blue light emitting phosphorescent emitters.

Hence, a further subject of the present invention is directed to an holetransport layer, comprising a compound of formula I according to thepresent invention.

A further subject of the present invention is directed to an emittinglayer, comprising a compound of formula I according to the presentinvention. In said embodiment a compound of formula I is preferably usedas host material in combination with a phosphorescent emitter.

The compounds of formula I have preferably a molecular weight below 1500g/mol.

A further subject of the present invention is directed to an electronblocking layer, comprising a compound of formula I according to thepresent invention.

R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are preferably H. Accordingly, compoundsof formula

are preferred, wherein X¹ and X² are as defined above.

R¹⁵ and R^(16′)(R¹⁶) may be a C₆-C₂₄aryl group, which can optionally besubstituted by G, or a C₂-C₃₀heteroaryl group, which can optionally besubstituted by G. If R^(16′) represents a heteroaryl group, which isdirectly bonded to the benzimidazo[1,2-a]benzimidazole skeleton(o=p=q=r=0), R^(16′) is preferably bonded via a carbon atom of theheteroaryl group to the benzimidazo[1,2-a]benzimidazole skeleton.

The C₆-C₂₄aryl groups R¹⁵ and R^(16′), which optionally can besubstituted by G, are typically phenyl, 4-methylphenyl, 4-methoxyphenyl,naphthyl, especially 1-naphthyl, or 2-naphthyl, biphenylyl, terphenylyl,pyrenyl, 2- or 9-fluorenyl, phenanthryl, or anthryl, which may beunsubstituted or substituted.

The C₂-C₃₀heteroaryl group groups R¹⁵ and R^(16′), which optionally canbe substituted by G, represent a ring with five to seven ring atoms or acondensed ring system, wherein nitrogen, oxygen or sulfur are thepossible hetero atoms, and is typically a heterocyclic group with fiveto 30 atoms having at least six conjugated n-electrons such as thienyl,benzothiophenyl, dibenzothiophenyl, thianthrenyl, furyl, furfuryl,2H-pyranyl, benzofuranyl, isobenzofuranyl, dibenzofuranyl,phenoxythienyl, pyrrolyl, imidazolyl, pyrazolyl, pyridyl, bipyridyl,triazinyl, pyrimidinyl, pyrazinyl, pyridazinyl, indolizinyl, isoindolyl,indolyl, indazolyl, purinyl, quinolizinyl, chinolyl, isochinolyl,phthalazinyl, naphthyridinyl, chinoxalinyl, chinazolinyl, cinnolinyl,pteridinyl, carbolinyl, benzotriazolyl, benzoxazolyl, phenanthridinyl,acridinyl, pyrimidinyl, phenanthrolinyl, phenazinyl, isothiazolyl,phenothiazinyl, isoxazolyl, furazanyl,benzimidazo[1,2-a]benzimidazo-5-yl, benzimidazo[1,2-a]benzimidazo-2-yl,carbazolyl, or phenoxazinyl, which can be unsubstituted or substituted.

The C₆-C₂₄aryl and C₂-C₃₀heteroaryl groups may be substituted by G.

Prefered C₂-C₃₀heteroaryl groups are pyridyl, triazinyl, pyrimidinyl,benzimidazo[1,2-a]benzimidazo-5-yl

benzimidazo[1,2-a]benzimidazo-2-yl

carbazolyl, dibenzofuranyl, which can be unsubstituted or substitutedespecially by C₆-C₁₀aryl, or C₆-C₁₀aryl, which is substituted byC₁-C₄alkyl; or C₂-C₁₄heteroaryl.

A¹, A², A³, A⁴ A⁵, A⁶, A⁷ and A⁸ are independently of each other aC₆-C₂₄arylen group, which can optionally be substituted by G, or aC₂-C₃₀heteroarylen group, which can optionally be substituted by G. TheC₆-C₂₄arylen groups A¹, A², A³, A⁴, A⁵, A⁶, A⁷ and A⁸, which optionallycan be substituted by G, are typically phenylene, 4-methylphenylene,4-methoxyphenylene, naphthylene, especially 1-naphthylene, or2-naphthylene, biphenylylene, terphenylylene, pyrenylene, 2- or9-fluorenylene, phenanthrylene, or anthrylene, which may beunsubstituted or substituted.

The C₂-C₃₀heteroarylen groups A¹, A², A³, A⁴ A⁵, A⁶, A⁷ and A⁸, whichoptionally can be substituted by G, represent a ring with five to sevenring atoms or a condensed ring system, wherein nitrogen, oxygen orsulfur are the possible hetero atoms, and is typically a heterocyclicgroup with five to 30 atoms having at least six conjugated-electronssuch as thienylene, benzothiophenylene, dibenzothiophenylene,thianthrenylene, furylene, furfurylene, 2H-pyranylene, benzofuranylene,isobenzofuranylene, dibenzofuranylene, phenoxythienylene, pyrrolylene,imidazolylene, pyrazolylene, pyridylene, bipyridylene, triazinylene,pyrimidinylene, pyrazinylene, pyridazinylene, indolizinylene,isoindolylene, indolylene, indazolylene, purinylene, quinolizinylene,chinolylene, isochinolylene, phthalazinylene, naphthyridinylene,chinoxalinylene, chinazolinylene, cinnolinylene, pteridinylene,carbolinylene, benzotriazolylene, benzoxazolylene, phenanthridinylene,acridinylene, pyrimidinylene, phenanthrolinylene, phenazinylene,isothiazolylene, phenothiazinylene, isoxazolylene, furazanylene,carbazolylene, benzimidazo[1,2-a]benzimidazo-2,5-ylene, orphenoxazinylene, which can be unsubstituted or substituted.

Preferred C₆-C₂₄arylen groups are 1,3-phenylene, 3,3′-biphenylylene,3,3′-m-terphenylene, 2- or 9-fluorenylene, phenanthrylene, which may beunsubstituted or substituted.

Preferred C₂-C₃₀heteroarylen groups are pyridylene, triazinylene,pyrimidinylene, carbazolylene, dibenzofuranylene andbenzimidazo[1,2-a]benzimidazo-2,5-ylene

which can be unsubstituted or substituted, especially by C₆-C₁₀aryl,C₆-C₁₀aryl which is substituted by C₁-C₄alkyl; or C₂-C₁₄heteroaryl.

Benzimidazo[1,2-a]benzimidazo-5-yl, benzimidazo[1,2-a]benzimidazo-2-yl,carbazolyl and dibenzofuranyl are examples of a C₂-C₁₄heteroaryl group.Phenyl, 1-naphthyl and 2-naphthyl are examples of a C₆-C₁₀aryl group.

More preferred C₂-C₃₀heteroarylen groups arebenzimidazo[1,2-a]benzimidazo-2,5-ylene, carbazolylene anddibenzofuranylene which optionally can be substituted by C₆-C₁₀aryl,which can optionally be substituted by one, or more C₁-C₄alkyl groups,or dibenzofuranyl.

The C₆-C₂₄arylen and C₂-C₃₀heteroarylen groups may be substituted by G.

X¹ is preferably a group of the formula-A¹-(A²)_(p)-(A³)_(q)-(A⁴)_(r)—R¹⁶, or-(A¹)_(o)-(A²)_(p)-(A³)_(q)(A⁴)_(r)—R^(16′), o is 0, or 1, p is 0, or 1,q is 0, or 1, r is 0, or 1,

A¹, A², A³ and A⁴ are independently of each other a group of the formula

R¹⁶ is a group of the formula

R^(16′) is a group of the formula

R²¹ and R^(21′) are independently of each other H, a phenyl group, or aC₁-C₁₈alkyl group;

R²² and R²³ are independently of each other H, or a group of the formula

X is O, S, or NR²⁴, and

R²⁴ is a C₆-C₂₄aryl group, or a C₂-C₃₀heteroaryl group, which canoptionally be substituted by G, wherein G is as defined in claim 1.

More preferred, X¹ is a group of the formula-A¹-(A²)_(p)-(A³)_(q)-(A⁴)_(r)—R¹⁶, or-(A¹)_(o)-(A²)_(p)-(A³)_(q)(A⁴)_(r)—R^(16′), o is 0, or 1, p is 0, or 1,q is 0, or 1, r is 0, or 1,

A¹, A², A³ and A⁴ are independently of each other a group of the formula

especially

R¹⁶ is a group of the formula

R^(16′) is a group of the formula

and R²¹ is a group of the formula

Most preferred X¹ is a group of the formula

especially

X² is preferably a group of formula-(A⁵)_(v)-(A⁶)_(s)-(A⁷)_(t)-(A⁸)_(u)—R₁₅,

v is 0, or 1, s is 0, or 1, t is 0, or 1, u is 0, or 1,

A⁵, A⁶, A⁷ and A⁸ are independently of each other

R¹⁵ is a group of the formula

R²⁶, R²⁷, R²⁹ and R³² are independently of each other H, or a group ofthe formula

R³⁰ and R³³ are independently of each other a group of formula

and

R³¹ is a group of formula

More preferred X² is a group of formula-(A⁵)_(v)-(A⁶)_(s)-(A⁷)_(t)-(A⁸)_(u)—R¹⁵, v is 0, or 1, s is 0, or 1, tis 0, or 1, u is 0, or 1,

A⁵, A⁶, A⁷ and A⁸ are independently of each other

R¹⁵ is a group of the formula

An example of X² is a group of formula

Most preferred X² is a group of formula

Compounds of formula (Ia) are preferred, where X¹ and X² have thepreferred meanings given above. Compounds of formula (Ia) are morepreferred, where X¹ and X² have the more preferred meanings given above.Compounds of formula (Ia) are most preferred, where X¹ and X² have themost preferred meanings given above.

In another preferred embodiment the present invention is directed tocompounds of formula (Ia), comprising two groups

i.e compounds of formula

wherein X^(2′) is a group of the formula -(A⁸)_(u)—R¹⁵, —NR¹⁰R¹¹, orSi(R¹²)(R¹³)(R¹⁴),

X⁴ is a group of formula A¹-(A²)_(p)-, and

p, u, A¹, A², A⁸, R¹⁰, R¹¹, R¹², R¹³, R¹⁴ and R¹⁵ are as defined above.The groups X^(2′) may be different, but are preferably the same. Withrespect to p, u, A¹, A², A⁸, R¹⁰, R¹¹, R¹², R¹³, R¹⁴ and R¹⁵ the samepreferences apply as with respect to the compounds of formula (I) and(Ia), respectively.

In another preferred embodiment the present invention is directed tocompounds of formula (Ia), comprising two groups

i.e compounds of formula

wherein X^(1′) is a group of formula -A¹—R¹⁶, or -(A⁴)_(r)—R^(16′); X⁵is a group of formula -A⁵-(A⁶)_(s)-, and r, s, A¹, R¹⁶, A⁴, R^(16′), A⁵and A⁶ are as defined above. The groups X^(1′) may be different, but arepreferably the same. With respect to r, s, A¹, R¹⁶, A⁴, R^(16′), A⁵ andA⁶ the same preferences apply as with respect to the compounds offormula (I) and (Ia), respectively.

Examples of especially preferred compounds are compounds A-1 to A-45shown in claim 8, which are particularly suitable as host and holetransport material. Compounds A-1, A-2, A-9, A-10, A-11, A-24, A-42,A-43, A-44 and A-45 are most preferred. Additional examples of preferredcompounds are compounds A-46 to A-51 shown in claim 8.

Halogen is fluorine, chlorine, bromine and iodine.

C₁-C₂₅alkyl (C₁-C₁₈alkyl) is typically linear or branched, wherepossible. Examples are methyl, ethyl, n-propyl, isopropyl, n-butyl,sec.-butyl, isobutyl, tert.-butyl, n-pentyl, 2-pentyl, 3-pentyl,2,2-dimethylpropyl, 1,1,3,3-tetramethylpentyl, n-hexyl, 1-methylhexyl,1,1,3,3,5,5-hexamethylhexyl, n-heptyl, isoheptyl,1,1,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl,1,1,3,3-tetramethylbutyl and 2-ethylhexyl, n-nonyl, decyl, undecyl,dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, oroctadecyl. C₁-C₈alkyl is typically methyl, ethyl, n-propyl, isopropyl,n-butyl, sec.-butyl, isobutyl, tert.-butyl, n-pentyl, 2-pentyl,3-pentyl, 2,2-dimethyl-propyl, n-hexyl, n-heptyl, n-octyl,1,1,3,3-tetramethylbutyl and 2-ethylhexyl. C₁-C₄alkyl is typicallymethyl, ethyl, n-propyl, isopropyl, n-butyl, sec.-butyl, isobutyl,tert.-butyl.

C₁-C₂₅alkoxy groups (C₁-C₁₈alkoxy groups) are straight-chain or branchedalkoxy groups, e.g. methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy,sec-butoxy, tert-butoxy, amyloxy, isoamyloxy or tert-amyloxy, heptyloxy,octyloxy, isooctyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy,tetradecyloxy, pentadecyloxy, hexadecyloxy, heptadecyloxy andoctadecyloxy. Examples of C₁-C₈alkoxy are methoxy, ethoxy, n-propoxy,isopropoxy, n-butoxy, sec.-butoxy, isobutoxy, tert.-butoxy, n-pentyloxy,2-pentyloxy, 3-pentyloxy, 2,2-dimethylpropoxy, n-hexyloxy, n-heptyloxy,n-octyloxy, 1,1,3,3-tetramethylbutoxy and 2-ethylhexyloxy, preferablyC₁-C₄alkoxy such as typically methoxy, ethoxy, n-propoxy, isopropoxy,n-butoxy, sec.-butoxy, isobutoxy, tert.-butoxy.

The term “cycloalkyl group” is typically C₄-C₁₈cycloalkyl, especiallyC₅-C₁₂cycloalkyl, such as cyclopentyl, cyclohexyl, cycloheptyl,cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, cyclododecyl,preferably cyclopentyl, cyclohexyl, cycloheptyl, or cyclooctyl, whichmay be unsubstituted or substituted.

C₆-C₂₄aryl (C₆-C₁₈aryl), which optionally can be substituted, istypically phenyl, 4-methylphenyl, 4-methoxyphenyl, naphthyl, especially1-naphthyl, or 2-naphthyl, biphenylyl, terphenylyl, pyrenyl, 2- or9-fluorenyl, phenanthryl, or anthryl, which may be unsubstituted orsubstituted.

C₂-C₃₀heteroaryl represents a ring with five to seven ring atoms or acondensed ring system, wherein nitrogen, oxygen or sulfur are thepossible hetero atoms, and is typically a heterocyclic group with fiveto 30 atoms having at least six conjugated i-electrons such as thienyl,benzothiophenyl, dibenzothiophenyl, thianthrenyl, furyl, furfuryl,2H-pyranyl, benzofuranyl, isobenzofuranyl, dibenzofuranyl,phenoxythienyl, pyrrolyl, imidazolyl, pyrazolyl, pyridyl, bipyridyl,triazinyl, pyrimidinyl, pyrazinyl, pyridazinyl, indolizinyl, isoindolyl,indolyl, indazolyl, purinyl, quinolizinyl, chinolyl, isochinolyl,phthalazinyl, naphthyridinyl, chinoxalinyl, chinazolinyl, cinnolinyl,pteridinyl, carbazolyl, carbolinyl, benzotriazolyl, benzoxazolyl,phenanthridinyl, acridinyl, pyrimidinyl, phenanthrolinyl, phenazinyl,isothiazolyl, phenothiazinyl, isoxazolyl, furazanyl,4-imidazo[1,2-a]benzimidazoyl, 5-benzimidazo[1,2-a]benzimidazoyl,carbazolyl, or phenoxazinyl, which can be unsubstituted or substituted.

Possible substituents of the above-mentioned groups are C₁-C₈alkyl, ahydroxyl group, a mercapto group, C₁-C₈alkoxy, C₁-C₈alkylthio, halogen,halo-C₁-C₈alkyl, or a cyano group. The C₆-C₂₄aryl (C₆-C₁₈aryl) andC₂-C₃₀heteroaryl groups are preferably substituted by one, or moreC₁-C₈alkyl groups.

If a substituent occurs more than one time in a group, it can bedifferent in each occurrence. The wording “substituted by G” means thatone, or more, especially one to three substituents G might be present.

As described above, the aforementioned groups may be substituted by Eand/or, if desired, interrupted by D. Interruptions are of coursepossible only in the case of groups containing at least 2 carbon atomsconnected to one another by single bonds; C₆-C₁₈aryl is not interrupted;interrupted arylalkyl contains the unit D in the alkyl moiety.C₁-C₁₈alkyl substituted by one or more E and/or interrupted by one ormore units D is, for example, (CH₂CH₂O)₁₋₉—R^(x), where R^(x) is H orC₁-C₁₀alkyl or C₂-C₁₀alkanoyl (e.g. CO—CH(C₂H₅)C₄H₉),CH₂—CH(OR^(y′))—CH₂—O—R^(y), where R^(y) is C₁-C₁₈alkyl,C₅-C₁₂cycloalkyl, phenyl, C₇-C₁₅phenylalkyl, and R^(y′) embraces thesame definitions as R^(y) or is H; C₁-C₈alkylene-COO—R^(z), e.g.CH₂COOR_(z), CH(CH₃)COOR^(z), C(CH₃)₂COOR^(z), where R^(z) is H,C₁-C₁₈alkyl, (CH₂CH₂O)₁₋₉—R^(x), and R^(x) embraces the definitionsindicated above;

CH₂CH₂—O—CO—CH═CH₂; CH₂CH(OH)CH₂—O—CO—C(CH₃)═CH₂.

The synthesis of

is described, for example, in Achour, Reddouane; Zniber, Rachid,Bulletin des Societes Chimiques Belges 96 (1987) 787-92.

Suitable base skeletons of the formula

are either commercially available (especially in the cases when X is S,O, NH), or can be obtained by processes known to those skilled in theart. Reference is made to WO2010079051 and EP1885818.

The halogenation can be performed by methods known to those skilled inthe art. Preference is given to brominating or iodinating in the 3 and 6positions (dibromination) or in the 3 or 6 positions (monobromination)of the base skeleton of the formula (II) 2,8 positions (dibenzofuran anddibenzothiophene) or 3,6 positions (carbazole).

Optionally substituted dibenzofurans, dibenzothiophenes and carbazolescan be dibrominated in the 2,8 positions (dibenzofuran anddibenzothiophene) or 3,6 positions (carbazole) with bromine or NBS inglacial acetic acid or in chloroform. For example, the bromination withBr₂ can be effected in glacial acetic acid or chloroform at lowtemperatures, e.g. 0° C. Suitable processes are described, for example,in M. Park, J. R. Buck, C. J. Rizzo, Tetrahedron, 54 (1998) 12707-12714for X═NPh, and in W. Yang et al., J. Mater. Chem. 13 (2003) 1351 forX═S. In addition, 3,6-dibromocarbazole, 3,6-dibromo-9-phenylcarbazole,2,8-dibromodibenzothiophene, 2,8-dibromodibenzofuran, 2-bromocarbazole,3-bromodibenzothiophene, 3-bromodibenzofuran, 3-bromocarbazole,2-bromodibenzothiophene and 2-bromodibenzofuran are commerciallyavailable.

Monobromination in the 4 position of dibenzofuran (and analogously fordibenzothiophene) is described, for example, in J. Am. Chem. Soc. 1984,106, 7150. Dibenzofuran (dibenzothiophene) can be monobrominated in the3 position by a sequence known to those skilled in the art, comprising anitration, reduction and subsequent Sandmeyer reaction.

Monobromination in the 2 position of dibenzofuran or dibenzothiopheneand monobromination in the 3 position of carbazole are effectedanalogously to the dibromination, with the exception that only oneequivalent of bromine or NBS is added.

Alternatively, it is also possible to utilize iodinated dibenzofurans,dibenzothiophenes and carbazoles. The preparation is described, interalia, in Tetrahedron. Lett. 47 (2006) 6957-6960, Eur. J. Inorg. Chem. 24(2005) 4976-4984, J. Heterocyclic Chem. 39 (2002) 933-941, J. Am. Chem.Soc. 124 (2002) 11900-11907, J. Heterocyclic Chem, 38 (2001) 77-87.

For the nucleophilic substitution, Cl- or F-substituted dibenzofurans,dibenzothiophenes and carbazoles are required. The chlorination isdescribed, inter alia, in J. Heterocyclic Chemistry, 34 (1997) 891-900,Org. Lett., 6 (2004) 3501-3504; J. Chem. Soc. [Section] C: Organic, 16(1971) 2775-7, Tetrahedron Left. 25 (1984) 5363-6, J. Org. Chem. 69(2004) 8177-8182. The fluorination is described in J. Org. Chem. 63(1998) 878-880 and J. Chem. Soc., Perkin Trans. 2, 5 (2002) 953-957.

The introduction of the group

is performed in the presence of a base. Suitable bases are known tothose skilled in the art and are preferably selected from the groupconsisting of alkali metal and alkaline earth metal hydroxides such asNaOH, KOH, Ca(OH)₂, alkali metal hydrides such as NaH, KH, alkali metalamides such as NaNH₂, alkali metal or alkaline earth metal carbonatessuch as K₂CO₃ or Cs₂CO₃, and alkali metal alkoxides such as NaOMe,NaOEt. In addition, mixtures of the aforementioned bases are suitable.Particular preference is given to NaOH, KOH, NaH or K₂CO₃.

Heteroarylation can be effected, for example, by copper-catalyzedcoupling of

to a halogenated compound of the formula

(Ullmann reaction).

The N-arylation was, for example, disclosed in H. Gilman and D. A.Shirley, J. Am. Chem. Soc. 66 (1944) 888; D. Li et al., Dyes andPigments 49 (2001) 181-186 and Eur. J. Org. Chem. (2007) 2147-2151. Thereaction can be performed in solvent or in a melt. Suitable solventsare, for example, (polar) aprotic solvents such as dimethyl sulfoxide,dimethylformamide, NMP, tridecane or alcohols.

The synthesis of 9-(8-bromodibenzofuran-2-yl)carbazole,

is described in WO2010079051. The synthesis of2-bromo-8-iodo-dibenzofurane,

is described in EP1885818.

A possible synthesis route for the compound of formula

is shown in the following scheme:

Reference is made to Angew. Chem. Int. Ed. 46 (2007)1627-1629 andSynthesis 20 (2009) 3493.

Diboronic acid or diboronate group containing dibenzofurans,dibenzothiophenes and carbazoles can be readily prepared by anincreasing number of routes. An overview of the synthetic routes is, forexample, given in Angew. Chem. Int. Ed. 48 (2009) 9240-9261.

By one common route diboronic acid or diboronate group containingdibenzofurans, dibenzothiophenes, and carbazoles can be obtained byreacting halogenated dibenzofurans, dibenzothiophenes and carbazoleswith (Y¹O)₂B—B(OY¹)₂,

in the presence of a catalyst, such as, for example,[1,1′-bis(diphenylphosphino)ferrocene]dichloropalladium(II), complex(Pd(Cl)₂(dppf)), and a base, such as, for example, potassium acetate, ina solvent, such as, for example, dimethyl formamide, dimethyl sulfoxide,dioxane and/or toluene (cf. Prasad Appukkuttan et al., Synlett 8 (2003)1204), wherein Y¹ is independently in each occurrence a C₁-C₁₈alkylgroupand Y² is independently in each occurrence a C₂-C₁₀alkylene group, suchas —CY³Y⁴—CY⁵Y⁶—, or —CY⁷Y⁸—CY⁹Y¹⁰—CY¹¹Y¹²—, wherein Y³, Y⁴, Y⁵, Y⁶, Y⁷,Y⁸, Y⁹, Y¹⁰, Y¹¹ and Y¹² are independently of each other hydrogen, or aC₁-C₁₈alkylgroup, especially —C(CH₃)₂C(CH₃)₂—, —C(CH₃)₂CH₂C(CH₃)₂—, or—CH₂C(CH₃)₂CH₂—, and Y¹³ and Y¹⁴ are independently of each otherhydrogen, or a C₁-C₁₈alkylgroup.

Diboronic acid or diboronate group containing dibenzofurans,dibenzothiophenes and carbazoles can also be prepared by reactinghalogenated dibenzofurans, dibenzothiophenes and carbazoles with alkyllithium reagents, such as, for example, n-butyl lithium, or t-buthyllithium, followed by reaction with boronic esters, such as, for example,B(isopropoxy)₃, B(methoxy)₃, or

(cf. Synthesis (2000) 442-446).

Diboronic acid or diboronate group containing dibenzofurans,dibenzothiophenes and carbazoles can also be prepared by reactingdibenzofurans, dibenzothiophenes and carbazoles with lithium amides,such as, for example, lithium diisopropylamide (LDA) followed byreaction with boronic esters such as, for example, B(isopropoxy)₃,B(methoxy)₃, or

(J. Org. Chem. 73 (2008) 2176-2181).

Diboronic acid or diboronate group containing dibenzofurans,dibenzothiophenes and carbazoles, such as, for example,

can be reacted with equimolar amounts of halogenated dibenzofurans,dibenzothiophenes, carbazoles and 4H-imidazo[1,2-a]imidazoles, such as,for example,

in a solvent and in the presence of a catalyst. The catalyst may be oneof the μ-halo(triisopropylphosphine)(η³-allyl)palladium(II) type (seefor example WO99/47474).

Preferably, the Suzuki reaction is carried out in the presence of anorganic solvent, such as an aromatic hydrocarbon or a usual polarorganic solvent, such as benzene, toluene, xylene, tetrahydrofurane, ordioxane, or mixtures thereof, most preferred toluene. Usually, theamount of the solvent is chosen in the range of from 1 to 10 l per molof boronic acid derivative. Also preferred, the reaction is carried outunder an inert atmosphere such as nitrogen, or argon. Further, it ispreferred to carry out the reaction in the presence of an aqueous base,such as an alkali metal hydroxide or carbonate such as NaOH, KOH,Na₂CO₃, K₂CO₃, Cs₂CO₃ and the like, preferably an aqueous K₂CO₃ solutionis chosen. Usually, the molar ratio of the base to boronic acid orboronic ester derivative is chosen in the range of from 0.5:1 to 50:1,very especially 1:1. Generally, the reaction temperature is chosen inthe range of from 40 to 180° C., preferably under reflux conditions.Preferred, the reaction time is chosen in the range of from 1 to 80hours, more preferably from 20 to 72 hours. In a preferred embodiment ausual catalyst for coupling reactions or for polycondensation reactionsis used, preferably Pd-based, which is described in WO2007/101820. Thepalladium compound is added in a ratio of from 1:10000 to 1:50,preferably from 1:5000 to 1:200, based on the number of bonds to beclosed. Preference is given, for example, to the use of palladium(II)salts such as PdAc₂ or Pd₂dba₃ and to the addition of ligands selectedfrom the group consisting of

wherein

The ligand is added in a ratio of from 1:1 to 1:10, based on Pd. Alsopreferred, the catalyst is added as in solution or suspension.Preferably, an appropriate organic solvent such as the ones describedabove, preferably benzene, toluene, xylene, THF, dioxane, morepreferably toluene, or mixtures thereof, is used. The amount of solventusually is chosen in the range of from 1 to 10 l per mol of boronic acidderivative. Organic bases, such as, for example, tetraalkylammoniumhydroxide, and phase transfer catalysts, such as, for example TBAB, canpromote the activity of the boron (see, for example, Lead-beater &Marco; Angew. Chem. Int. Ed. Eng. 42 (2003) 1407 and references citedtherein). Other variations of reaction conditions are given by T. I.Wallow and B. M. Novak in J. Org. Chem. 59 (1994) 5034-5037; and M.Remmers, M. Schulze, G. Wegner in Macromol. Rapid Commun. 17 (1996)239-252 and G. A. Molander und B. Canturk, Angew. Chem., 121 (2009)9404-9425.

A possible synthetic route for compound A-42 is shown in the reactionscheme below:

A possible synthetic route for compound B-1 is shown in the reactionscheme below:

The halogen/metal exchange is done with nBuLi/THF at −78° C., ortBuLi/THF at −78° C. Reference is made to WO2010/079051, where thesynthesis of such compounds is described.

Compounds of formula

are new, intermediates in the production of compounds of formula (I) andform a further subject of the present invention.

X¹ is as defined above, or is a group of formulaA¹-(A²)_(p)-(A³)_(q)-(A⁴)_(r)—R^(16″),

X³ is a group of formula -(A⁵)_(v)-(A⁶)_(s)-(A⁷)_(t)-(A⁸)_(u)—R^(15′),wherein R^(15′) and R^(16″) are independently of each other Cl, Br, I,ZnX¹², X¹² is a halogen atom; —SnR²⁰⁷R²⁰⁶R²⁰⁹, wherein R²⁰⁷, R²⁰⁸ andR²⁰⁹ are identical or different and are H or C₁-C₈alkyl, wherein tworadicals optionally form a common ring and these radicals are optionallybranched or branched; —B(OH)₂, —B(OY¹)₂,

—BF₄Na, or —BF₄K, wherein Y¹ is independently in each occurrence aC₁-C₁₈alkyl group and Y² is independently in each occurrence aC₂-C₁₀alkylene group, such as —CY³Y⁴—CY⁵Y⁶—, or —CY⁷Y⁸—CY⁹Y¹⁰—CY¹¹Y¹²—,wherein Y³, Y⁴, Y⁵, Y⁶, Y⁷, Y⁸, Y⁹, Y¹⁰, Y¹¹ and Y¹² are independentlyof each other hydrogen, or a C₁-C₁₀alkyl group, especially—C(CH₃)₂C(CH₃)₂—, —C(CH₃)₂CH₂C(CH₃)₂—, or —CH₂C(CH₃)₂CH₂—, and Y¹³ andY¹⁴ are independently of each other hydrogen, or a C₁-C₁₀alkyl group.

p, q, r, A¹, A², A³, A⁴, s, t, u, v, A⁵, A⁶, A⁷, A⁸, R¹, R², R³, R⁴, R⁵,R⁶ and R⁷ are as defined above. With respect to p, q, r, A¹, A², A³, A⁴,s, t, u, v, A⁵, A⁶, A⁷, A⁸, R¹, R², R³, R⁴, R⁵, R⁶, R⁷ and X¹ the samepreferences apply as for the compounds of formula (I).

Examples of the intermediates are shown below:

A process for the preparation of a compound of formula

wherein X³ is Cl, Br, or I; comprises halogenation of a compound offormula

With respect to R¹, R², R³, R⁴, R⁵, R⁶, R⁷ and X¹ the same preferencesapply as with respect to the compounds of formula (I).

The bromination of 5-phenybenzimidazolo[1,2-a]benzimidazole can becarried out in analogy to the bromination of carbazole, which is, forexample, described in J. Mater. Chem. 18 (2008) 1296-1301.

Other bromination methods are, for example, described in HelveticaChimica Acta 89 (2006) 1123 and SYNLETT 17 (2006) 2841-2845. 10.206

Selective halogenation of (III) with a halogenation agent results in thecompounds of formula (II). Halogenation agents are, for example,N-chlorosuccinimide (NCS) (Synlett 18 (2005) 2837-2842); Br₂ (Synthesis10 (2005) 1619-1624), N-bromosuccinimide (NBS)(Organic Letters 12 (2010)2194-2197; Synlett (2006) 2841-2845), 1,3-dibromo-5,5-dimethylhydantoin(DBH) (Organic Process Research & Development 10 (2006) 822-828,US2002/0151456), CuBr₂ (Synthetic Communications 37 (2007) 1381-1388);R₄NBr₃ (Can. J. Chem. 67 (1989) 2062), N-iodosuccinimide (NIS)(Synthesis 12 (2001) 1794-1799, J. Heterocyclic Chem. 39 (2002) 933),KI/KIO₃(Org. Lett. 9 (2007) 797, Macromolecules 44 (2011) 1405-1413),NaIO₄/I₂/H₂SO₄ or NaIO₄/KI/H₂SO₄ (J. Heterocyclic Chem. 38 (2001) 77; J.Org. Chem. 75 (2010) 2578-2588); iodine monochloride (ICI; Synthesis(2008) 221-224). Additional methods are described in J. Org. Chem. 74(2009) 3341-3349; J. Org. Chem. 71 (2006) 7422-7432, Eur. J. Org. Chem.(2008) 1065-1071, Chem. Asian J. 5 (2010) 2162-2167, Synthetic. Commun.28 (1998) 3225.

Examples of solvents, which can be used in the halogenation, aredimethylformamide (DMF), CH₂Cl₂, CHCl₃, CCl₄, ethanol (EtOH), aceticacid (AcOH), H₂SO₄, C₆H₅Cl and mixtures thereof. The halogenation can bedone in the presence of acids and lewis acids, respectively, such as,for example, H₂SO₄, ZrCl₄, TiCl₄, AlCl₃, HfCl₄ and AlCl₃ (Synlett 18(2005) 2837-2842).

Preferably, a compound of formula

especially

is reacted with NBS in a solvent, such as, for example, DMF, aceticacid, chloroform, dichloromethane, chlorobenzene, and mixtures thereof;at a temperature of −40° C. to 150° C. DMF represents the preferredsolvent.

The halogenated intermediates (III), wherein X³ is Cl, Br, or I, can betransformed to the boronic ester intermediates (III) by reactinghalogenated intermediates (II) with (Y¹O)₂B—B(OY¹)₂,

in the presence of a catalyst, such as, for example,[1,1′-bis(diphenylphosphino)ferrocene]dichloropalladium(II), complex(Pd(Cl)₂(dppf)), and a base, such as, for example, potassium acetate, ina solvent, such as, for example, dimethyl formamide, dimethyl sulfoxide,dioxane and/or toluene (cf. Prasad Appukkuttan et al., Synlett 8 (2003)1204).

An overview of the preparation of boronic reagents is given in Angew.Chem. 121 (2009) 9404-9425, Chem. Rev. 95 (1995) 2457-2483, Angew. Chem.Int. Ed. 41 (2002) 4176-4211, Tetrahedron 66 (2010) 8121-8136.

Diboronic acid or diboronate intermediates (III) can also be prepared byreacting halogenated intermediates (III) with alkyl lithium reagents,such as, for example, n-butyl lithium, or t-buthyl lithium, followed byreaction with boronic esters, such as, for example, B(isopropoxy)₃,B(methoxy)₃, or

(cf. Synthesis (2000) 442-446).

The compounds of formula I can be obtained starting from theintermediates and suitable co-reactants, for example, by Suzuki-,Stille-, or Negishi-coupling reactions.

A process for the preparation of a compound of formula

wherein X¹ is as defined above, may comprise (a) heating a compound offormula

in H₃PO₄, polyphosporic acid CH₃SO₃H/P₂O₅, CH₃SO₃H, or sulfuric acid toobtain a compound of formula

and (b) reacting the compound of formula XI to a compound of formula(I). Various examples for step b) are illustrated above. In step a) asolvent, or mixtures of solvents having a boiling point above 140° C.,such as, for example, xylene, or mesitylen, may be present. Compounds offormula

are stirred under an atmosphere of inert gas, such as, for example,nitrogen, or argon, at a temperature above 140° C., preferably above160° C., more preferably above 180° C., for a time of 30 minutes to 3weeks, preferably 1 to 48 h.

It has been found that the compounds of the formula I are particularlysuitable for use in applications in which charge carrier conductivity isrequired, especially for use in organic electronics applications, forexample selected from switching elements such as organic transistors,e.g. organic FETs and organic TFTs, organic solar cells and organiclight-emitting diodes (OLEDs), the compounds of the formula I beingparticularly suitable in OLEDs for use as matrix material in alight-emitting layer and/or as hole and/or exciton blocker materialand/or as electron and/or exciton blocker material, especially incombination with a phosphorescence emitter. In the case of use of theinventive compounds of the formula I in OLEDs, OLEDs which have goodefficiencies and a long lifetime and which can be operated especially ata low use and operating voltage are obtained. The inventive compounds ofthe formula I are suitable especially for use as matrix and/orhole/exciton blocker materials for blue and green emitters, for examplelight blue or deep blue emitters, these being especially phosphorescenceemitters. Furthermore, the compounds of the formula I can be used asconductor/complementary materials in organic electronics applicationsselected from switching elements and organic solar cells.

The compounds of the formula I can be used as matrix material and/orhole/exciton blocker material and/or electron/exciton blocker materialand/or hole injection material and/or electron injection material and/orhole conductor material (hole transport material) and/or electronconductor material (electron transport material), preferably as matrixmaterial and/or electron/exciton blocker and/or hole transportingmaterial in organic electronics applications, especially in OLEDs. Theinventive compounds of the formula I are more preferably used as matrixmaterials in organic electronics applications, especially in OLEDs.

In the emission layer or one of the emission layers of an OLED, it isalso possible to combine an emitter material with a matrix material ofthe compound of the formula I and a further matrix material which has,for example, a good hole conductor (hole transport) property. Thisachieves a high quantum efficiency of this emission layer.

When a compound of the formula I is used as matrix material in anemission layer and additionally as hole/exciton blocker material and/orelectron/exciton blocker material, owing to the chemical identity orsimilarity of the materials, an improved interface between the emissionlayer and the adjacent hole/exciton blocker material and/orelectron/exciton blocker material is obtained, which can lead to adecrease in the voltage with equal luminance and to an extension of thelifetime of the OLED. Moreover, the use of the same material forhole/exciton blocker material and/or electron/exciton blocker materialand for the matrix of an emission layer allows the production process ofan OLED to be simplified, since the same source can be used for thevapor deposition process of the material of one of the compounds of theformula I.

Suitable structures of organic electronic devices are known to thoseskilled in the art and are specified below.

The organic transistor generally includes a semiconductor layer formedfrom an organic layer with hole transport capacity and/or electrontransport capacity; a gate electrode formed from a conductive layer; andan insulating layer introduced between the semiconductor layer and theconductive layer. A source electrode and a drain electrode are mountedon this arrangement in order thus to produce the transistor element. Inaddition, further layers known to those skilled in the art may bepresent in the organic transistor.

The organic solar cell (photoelectric conversion element) generallycomprises an organic layer present between two plate-type electrodesarranged in parallel. The organic layer may be configured on a comb-typeelectrode. There is no particular restriction regarding the site of theorganic layer and there is no particular restriction regarding thematerial of the electrodes. When, however, plate-type electrodesarranged in parallel are used, at least one electrode is preferablyformed from a transparent electrode, for example an ITO electrode or afluorine-doped tin oxide electrode. The organic layer is formed from twosublayers, i.e. a layer with p-type semiconductor properties or holetransport capacity, and a layer formed with n-type semiconductorproperties or electron transport capacity. In addition, it is possiblefor further layers known to those skilled in the art to be present inthe organic solar cell. The layer with hole transport capacity maycomprise the compounds of formula I.

It is likewise possible that the compounds of the formula I are presentboth in the light-emitting layer (preferably as matrix material) and inthe blocking layer for electrons (as electron/exciton blockers).

The present invention further provides an organic light-emitting diodecomprising an anode An and a cathode Ka and a light-emitting layer Earranged between the anode An and the cathode Ka, and if appropriate atleast one further layer selected from the group consisting of at leastone blocking layer for holes/excitons, at least one blocking layer forelectrons/excitons, at least one hole injection layer, at least one holeconductor layer, at least one electron injection layer and at least oneelectron conductor layer, wherein the at least one compound of theformula I is present in the light-emitting layer E and/or in at leastone of the further layers. The at least one compound of the formula I ispreferably present in the light-emitting layer and/or the blocking layerfor holes.

The present application further relates to a light-emitting layercomprising at least one compound of the formula I.

Structure of the Inventive OLED

The inventive organic light-emitting diode (OLED) thus generally has thefollowing structure: an anode (An) and a cathode (Ka) and alight-emitting layer E arranged between the anode (An) and the cathode(Ka).

The inventive OLED may, for example—in a preferred embodiment—be formedfrom the following layers:

1. Anode

2. Hole conductor layer

3. Light-emitting layer

4. Blocking layer for holes/excitons

5. Electron conductor layer

6. Cathode

Layer sequences different than the aforementioned structure are alsopossible, and are known to those skilled in the art. For example, it ispossible that the OLED does not have all of the layers mentioned; forexample, an OLED with layers (1) (anode), (3) (light-emitting layer) and(6) (cathode) is likewise suitable, in which case the functions of thelayers (2) (hole conductor layer) and (4) (blocking layer forholes/excitons) and (5) (electron conductor layer) are assumed by theadjacent layers. OLEDs which have layers (1), (2), (3) and (6), orlayers (1), (3), (4), (5) and (6), are likewise suitable. In addition,the OLEDs may have a blocking layer for electrons/excitons between thehole conductor layer (2) and the Light-emitting layer (3).

It is additionally possible that a plurality of the aforementionedfunctions (electron/exciton blocker, hole/exciton blocker, holeinjection, hole conduction, electron injection, electron conduction) arecombined in one layer and are assumed, for example, by a single materialpresent in this layer. For example, a material used in the holeconductor layer, in one embodiment, may simultaneously block excitonsand/or electrons.

Furthermore, the individual layers of the OLED among those specifiedabove may in turn be formed from two or more layers. For example, thehole conductor layer may be formed from a layer into which holes areinjected from the electrode, and a layer which transports the holes awayfrom the hole-injecting layer into the light-emitting layer. Theelectron conduction layer may likewise consist of a plurality of layers,for example a layer in which electrons are injected by the electrode,and a layer which receives electrons from the electron injection layerand transports them into the light-emitting layer. These layersmentioned are each selected according to factors such as energy level,thermal resistance and charge carrier mobility, and also energydifference of the layers specified with the organic layers or the metalelectrodes. The person skilled in the art is capable of selecting thestructure of the OLEDs such that it is matched optimally to the organiccompounds used as emitter substances in accordance with the invention.

In order to obtain particularly efficient OLEDs, for example, the HOMO(highest occupied molecular orbital) of the hole conductor layer shouldbe matched to the work function of the anode, and the LUMO (lowestunoccupied molecular orbital) of the electron conductor layer should bematched to the work function of the cathode, provided that theaforementioned layers are present in the inventive OLEDs.

The anode (1) is an electrode which provides positive charge carriers.It may be formed, for example, from materials which comprise a metal, amixture of various metals, a metal alloy, a metal oxide or a mixture ofvarious metal oxides. Alternatively, the anode may be a conductivepolymer. Suitable metals comprise metals and alloys of the metals of themain groups, transition metals and of the lanthanoids, especially themetals of groups Ib, IVa, Va and Via of the periodic table of theelements, and the transition metals of group VIIIa. When the anode is tobe transparent, generally mixed metal oxides of groups IIb, IIIb and IVbof the periodic table of the elements (IUPAC version) are used, forexample indium tin oxide (ITO). It is likewise possible that the anode(1) comprises an organic material, for example polyaniline, asdescribed, for example, in Nature, Vol. 357, pages 477 to 479 (Jun. 11,1992). At least either the anode or the cathode should be at leastpartly transparent in order to be able to emit the light formed. Thematerial used for the anode (1) is preferably ITO.

Suitable hole conductor materials for layer (2) of the inventive OLEDsare disclosed, for example, in Kirk-Othmer Encyclopedia of ChemicalTechnology, 4th edition, Vol. 18, pages 837 to 860, 1996. Bothhole-transporting molecules and polymers can be used as the holetransport material. Hole-transporting molecules typically used areselected from the group consisting oftris[N-(1-naphthyl)-N-(phenylamino)]triphenylamine (1-NaphDATA),4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (α-NPD),N,N′-diphenyl-N,N′-bis(3-methylphenyl)[1,1′-biphenyl]-4,4′-diamine(TPD), 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC),N,N′-bis(4-methylphenyl)-N,N′-bis(4-ethylphenyl)-[1,1′-(3,3′-dimethyl)biphenyl]-4,4′-diamine(ETPD), tetrakis(3-methylphenyl)-N,N,N′,N′-2,5-phenylenediamine (PDA),α-phenyl-4-N,N-diphenylaminostyrene (TPS), p-(diethylamino)benzaldehydediphenylhydrazone (DEH), triphenylamine (TPA),bis[4-(N,N-diethylamino)-2-methylphenyl)(4-methylphenyl)methane (MPMP),1-phenyl-3-[p-(diethylamino)styryl]-5-[p-(diethylamino)phenyl]pyrazoline(PPR or DEASP), 1,2-trans-bis(9H-carbazol-9-yl)cyclobutane (DCZB),N,N,N′,N′-tetrakis(4-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine (TTB),4,4′,4″-tris(N,N-diphenylamino)triphenylamine (TDTA),4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA),N,N′-bis(naphthalen-2-yl)-N,N′-bis(phenyl)benzidine (β-NPB),N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-9,9-spirobifluorene(Spiro-TPD),N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-9,9-spirobifluorene(Spiro-NPB),N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-9,9-dimethylfluorene(DMFL-TPD), di[4-(N,N-ditolylamino)phenyl]cyclohexane,N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-9,9-dimethylfluorene,N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-2,2-dimethylbenzidine,N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)benzidine,N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)benzidine,2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ),4,4′,4″-tris(N-3-methylpheny-N-phenylamino)triphenylamine,4,4′,4″-tris(N-(2-naphthyl)-N-phenyl-amino)triphenylamine,pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile (PPDN),N,N,N′,N′-tetrakis(4-methoxyphenyl)benzidine (MeO-TPD),2,7-bis[N,N-bis(4-methoxyphenyl)amino]-9,9-spirobifluorene(MeO-Spiro-TPD),2,2′-bis[N,N-bis(4-methoxyphenyl)amino]-9,9-spirobifluorene(2,2′-MeO-Spiro-TPD),N,N′-diphenyl-N,N′-di[4-(N,N-ditolylamino)phenyl]benzidine (NTNPB),N,N′-diphenyl-N,N′-di[4-(N,N-diphenylamino)phenyl]benzidine (NPNPB),N,N′-di(naphthalen-2-yl)-N,N′-diphenylbenzene-1,4-diamine (β-NPP),N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-9,9-diphenylfluorene(DPFL-TPD),N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-9,9-diphenylfluorene(DPFL-NPB), 2,2′,7,7′-tetrakis(N,N-diphenylamino)-9,9′-spirobifluorene(Spiro-TAD), 9,9-bis[4-(N,N-bis(biphenyl-4-yl)amino)phenyl]-9H-fluorene(BPAPF), 9,9-bis[4-(N,N-bis(naphthalen-2-yl)amino)phenyl]-9H-fluorene(NPAPF), 9,9-bis[4-(N,N-bis(naphthalen-2-yl)-N,N′-bisphenylamino)phenyl]-9H-fluorene (NPBAPF),2,2′,7,7′-tetrakis[N-naphthalenyl(phenyl)amino]-9,9′-spirobifluorene(Spiro-2NPB), N,N′-bis(phenanthren-9-yl)-N,N′-bis(phenyl)benzidine(PAPB),2,7-bis[N,N-bis(9,9-spirobifluoren-2-yl)amino]-9,9-spirobifluorene(Spiro-5), 2,2′-bis[N,N-bis(biphenyl-4-yl)amino]-9,9-spirobifluorene(2,2′-Spiro-DBP), 2,2′-bis(N,N-diphenylamino)-9,9-spirobifluorene(Spiro-BPA), 2,2′,7,7′-tetra(N,N-ditolyl)aminospirobifluorene(Spiro-TTB), N,N,N′,N′-tetranaphthalen-2-ylbenzidine (TNB), porphyrincompounds and phthalocyanines such as copper phthalocyanines andtitanium oxide phthalocyanines. Hole-transporting polymers typicallyused are selected from the group consisting of polyvinylcarbazoles,(phenylmethyl)polysilanes and polyanilines. It is likewise possible toobtain hole-transporting polymers by doping hole-transporting moleculesinto polymers such as polystyrene and polycarbonate. Suitablehole-transporting molecules are the molecules already mentioned above.

In addition—in one embodiment—it is possible to use carbene complexes ashole conductor materials, the band gap of the at least one holeconductor material generally being greater than the band gap of theemitter material used. In the context of the present application, “bandgap” is understood to mean the triplet energy. Suitable carbenecomplexes are, for example, carbene complexes as described in WO2005/019373 A2, WO 2006/056418 A2, WO 2005/113704, WO 2007/115970, WO2007/115981 and WO 2008/000727. One example of a suitable carbenecomplex is Ir(dpbic)₃ with the formula:

which is disclosed, for example, in WO2005/019373. In principle, it ispossible that the hole conductor layer comprises at least one compoundof the formula I as hole conductor material.

The light-emitting layer (3) comprises at least one emitter material. Inprinciple, it may be a fluorescence or phosphorescence emitter, suitableemitter materials being known to those skilled in the art. The at leastone emitter material is preferably a phosphorescence emitter. Thephosphorescence emitter compounds used with preference are based onmetal complexes, and especially the complexes of the metals Ru, Rh, Ir,Pd and Pt, in particular the complexes of Ir, have gained significance.The compounds of the formula I can be used as the matrix in thelight-emitting layer.

Suitable metal complexes for use in the inventive OLEDs are described,for example, in documents WO 02/60910 A1, US 2001/0015432 A1, US2001/0019782 A1, US 2002/0055014 A1, US 2002/0024293 A1, US 2002/0048689A1, EP 1 191 612 A2, EP 1 191 613 A2, EP 1 211 257 A2, US 2002/0094453A1, WO 02/02714 A2, WO 00/70655 A2, WO 01/41512 A1, WO 02/15645 A1, WO2005/019373 A2, WO 2005/113704 A2, WO 2006/115301 A1, WO 2006/067074 A1,WO 2006/056418, WO 2006121811 A1, WO 2007095118 A2, WO 2007/115970, WO2007/115981, WO 2008/000727, WO2010129323, WO2010056669 and WO10086089.

Further suitable metal complexes are the commercially available metalcomplexes tris(2-phenylpyridine)iridium(III), iridium(III)tris(2-(4-tolyl)pyridinato-N,C^(2′)),bis(2-phenylpyridine)(acetylacetonato)iridium(III), iridium(III)tris(1-phenylisoquinoline), iridium(III)bis(2,2′-benzothienyl)pyridinato-N,C^(3′))(acetylacetonate),tris(2-phenylquinoline)iridium(III), iridium(III)bis(2-(4,6-difluorophenyl)pyridinato-N,C²)picolinate, iridium(III)bis(1-phenylisoquinoline)(acetylacetonate),bis(2-phenylquinoline)(acetylacetonato) iridium(III), iridium(III)bis(di-benzo[f,h]quinoxaline)(acetylacetonate), iridium(III)bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate) andtris(3-methyl-1-phenyl-4-trimethylacetyl-5-pyrazolino)terbium(III),bis[1-(9,9-dimethyl-9H-fluoren-2-yl)isoquinoline](acetylacetonato)iridium(III),bis(2-phenylbenzothiazolato)(acetylacetonato)iridium(III),bis(2-(9,9-dihexylfluorenyl)-1-pyridine)(acetylacetonato)iridium(III),bis(2-benzo[b]thiophen-2-ylpyridine)(acetylacetonato)iridium(III).

In addition, the following commercially available materials aresuitable: tris(dibenzoylacetonato)mono(phenanthroline)europium(III),tris(dibenzoylmethane)mono(phenanthroline)europium(III),tris(dibenzoylmethane)mono(5-aminophenanthroline)europium(III),tris(di-2-naphthoylmethane)mono(phenanthroline)europium(Ill),tris(4-bromobenzoylmethane)mono(phenanthroline)europium(III),tris(di(biphenyl)methane)mono(phenanthroline)europium(III),tris(dibenzoylmethane)mono(4,7-diphenylphenanthroline)europium(III),tris(dibenzoylmethane)mono(4,7-di-methylphenanthroline)europium(III),tris(dibenzoylmethane)mono(4,7-dimethylphenanthrolinedisulfonicacid)europium(III) disodium salt,tris[di(4-(2-(2-ethoxyethoxy)ethoxy)benzoylmethane)]mono(phenanthroline)europium(III)andtris[di[4-(2-(2-ethoxyethoxy)ethoxy)benzoylmethane)]mono(5-aminophenanthroline)europium(III),osmium(II)bis(3-(trifluoromethyl)-5-(4-tert-butylpyridyl)-1,2,4-triazolato)diphenylmethylphosphine,osmium(II)bis(3-(trifluoromethyl)-5-(2-pyridyl)-1,2,4-triazole)dimethylphenylphosphine,osmium(II)bis(3-(trifluoromethyl)-5-(4-tert-butylpyridyl)-1,2,4-triazolato)dimethylphenylphosphine,osmium(II)bis(3-(trifluoromethyl)-5-(2-pyridyl)pyrazolato)dimethylphenylphosphine,tris[4,4′-di-tert-butyl(2,2′)-bipyridine]ruthenium(III), osmium(II)bis(2-(9,9-dibutylfluorenyl)-1-isoquinoline(acetylacetonate).

The light emitting layer comprises preferably a compound of the formula

which are described in WO 2005/019373 A2, wherein the symbols have thefollowing meanings:

M is a metal atom selected from the group consisting of Co, Rh, Ir, Nb,Pd, Pt, Fe, Ru, Os, Cr, Mo, W, Mn, Tc, Re, Cu, Ag and Au in anyoxidation state possible for the respective metal atom;

Carbene is a carbene ligand which may be uncharged or monoanionic andmonodentate, bidentate or tridentate, with the carbene ligand also beingable to be a biscarbene or triscarbene ligand;

L is a monoanionic or dianionic ligand, which may be monodentate orbidentate;

K is an uncharged monodentate or bidentate ligand selected from thegroup consisting of phosphines; phosphonates and derivatives thereof,arsenates and derivatives thereof; phosphites; CO; pyridines; nitrilesand conjugated dienes which form a π complex with M¹;

n1 is the number of carbene ligands, where n1 is at least 1 and whenn1>1 the carbene ligands in the complex of the formula I can beidentical or different;

m1 is the number of ligands L, where m1 can be 0 or ≥1 and when m1>1 theligands L can be identical or different;

o is the number of ligands K, where o can be 0 or ≥1 and when o>1 theligands K can be identical or different;

where the sum n1+m1+o is dependent on the oxidation state andcoordination number of the metal atom and on the denticity of theligands carbene, L and K and also on the charge on the ligands, carbeneand L, with the proviso that n1 is at least 1.

Carbene complexes which are suitable triplet emitters are described, forexample, in WO 2006/056418 A2, WO 2005/113704, WO 2007/115970, WO2007/115981 and WO 2008/000727, WO2009050281, WO2009050290, WO2011051404and WO2011073149.

More preferred are metal-carbene complexes of the general formula

which are described in U.S. patent application Nos. 61/286,046,61/323,885 and Europen patent application 10187176.2(PCT/EP2010/069541), where M, n1, Y, A², A³, A⁴, A⁵, R⁵¹, R⁵², R⁵³, R⁵⁴,R⁵⁵, R⁵⁶, R⁵⁷, R⁵⁸, R⁵⁹, K, L, m1 and o are each defined as follows:

M is Ir, or Pt,

n1 is an integer selected from 1, 2 and 3,

Y is NR⁵¹, O, S or C(R²⁵)₂,

A², A³, A⁴, and A⁵ are each independently N or C, where 2 A=nitrogenatoms and at least one carbon atom is present between two nitrogen atomsin the ring,

R⁵¹ is a linear or branched alkyl radical optionally interrupted by atleast one heteroatom, optionally bearing at least one functional groupand having 1 to 20 carbon atoms, cycloalkyl radical optionallyinterrupted by at least one heteroatom, optionally bearing at least onefunctional group and having 3 to 20 carbon atoms, substituted orunsubstituted aryl radical optionally interrupted by at least oneheteroatom, optionally bearing at least one functional group and having6 to 30 carbon atoms, substituted or unsubstituted heteroaryl radicaloptionally interrupted by at least one heteroatom, optionally bearing atleast one functional group and having a total of 5 to 18 carbon atomsand/or heteroatoms,

R⁵², R⁵³, R⁵⁴ and R⁵⁵ are each, if A², A³, A⁴ and/or A⁵ is N, a freeelectron pair, or, if A², A³, A⁴ and/or A⁵ is C, each independentlyhydrogen, linear or branched alkyl radical optionally interrupted by atleast one heteroatom, optionally bearing at least one functional groupand having 1 to 20 carbon atoms, cycloalkyl radical optionallyinterrupted by at least one heteroatom, optionally bearing at least onefunctional group and having 3 to 20 carbon atoms, substituted orunsubstituted aryl radical optionally interrupted by at least oneheteroatom, optionally bearing at least one functional group and having6 to 30 carbon atoms, substituted or unsubstituted heteroaryl radicaloptionally interrupted by at least one heteroatom, optionally bearing atleast one functional group and having a total of 5 to 18 carbon atomsand/or heteroatoms, group with donor or acceptor action, or

R^(S3) and R⁵⁴ together with A³ and A⁴ form an optionally substituted,unsaturated ring optionally interrupted by at least one furtherheteroatom and having a total of 5 to 18 carbon atoms and/orheteroatoms,

R⁵⁶, R⁵⁷, R⁵⁸ and R⁵⁹ are each independently hydrogen, linear orbranched alkyl radical optionally interrupted by at least oneheteroatom, optionally bearing at least one functional group and having1 to 20 carbon atoms, cycloalkyl radical optionally interrupted by atleast one heteroatom, optionally bearing at least one functional groupand having 3 to 20 carbon atoms, cycloheteroalkyl radical optionallyinterrupted by at least one heteroatom, optionally bearing at least onefunctional group and having 3 to 20 carbon atoms, substituted orunsubstituted aryl radical optionally interrupted by at least oneheteroatom, optionally bearing at least one functional group and having6 to 30 carbon atoms, substituted or unsubstituted heteroaryl radicaloptionally interrupted by at least one heteroatom, optionally bearing atleast one functional group and having a total of 5 to 18 carbon atomsand/or heteroatoms, group with donor or acceptor action, or

R⁵⁶ and R⁵⁷, R⁵⁷ and R⁵⁸ or R⁵⁸ and R⁵⁹, together with the carbon atomsto which they are bonded, form a saturated, unsaturated or aromatic,optionally substituted ring optionally interrupted by at least oneheteroatom and having a total of 5 to 18 carbon atoms and/orheteroatoms, and/or

if A⁵ is C, R⁵⁵ and R⁵⁶ together form a saturated or unsaturated, linearor branched bridge optionally comprising heteroatoms, an aromatic unit,heteroaromatic unit and/or functional groups and having a total of 1 to30 carbon atoms and/or heteroatoms, to which is optionally fused asubstituted or unsubstituted, five- to eight-membered ring comprisingcarbon atoms and/or heteroatoms,

R²⁵ is independently a linear or branched alkyl radical optionallyinterrupted by at least one heteroatom, optionally bearing at least onefunctional group and having 1 to 20 carbon atoms, cycloalkyl radicaloptionally interrupted by at least one heteroatom, optionally bearing atleast one functional group and having 3 to 20 carbon atoms, substitutedor unsubstituted aryl radical optionally interrupted by at least oneheteroatom, optionally bearing at least one functional group and having6 to 30 carbon atoms, substituted or unsubstituted heteroaryl radicaloptionally interrupted by at least one heteroatom, optionally bearing atleast one functional group and having a total of 5 to 18 carbon atomsand/or heteroatoms,

K is an uncharged mono- or bidentate ligand,

L is a mono- or dianionic ligand, preferably monoanionic ligand, whichmay be mono- or bidentate,

m1 is 0, 1 or 2, where, when m1 is 2, the K ligands may be the same ordifferent,

o is 0, 1 or 2, where, when o is 2, the L ligands may be the same ordifferent.

The compound of formula IX is preferably a compound of the formula:

The homoleptic metal-carbene complexes may be present in the form offacial or meridional isomers, preference being given to the facialisomers.

In the case of the heteroleptic meta-carbene complexes, four differentisomers may be present, preference being given to the pseudo-facialisomers.

The light-emitting layer may comprise further components in addition tothe emitter material. For example, a fluroescent dye may be present inthe light-emitting layer in order to alter the emission color of theemitter material. In addition—in a preferred embodiment—a matrixmaterial can be used. This matrix material may be a polymer, for examplepoly(N-vinylcarbazole) or polysilane. The matrix material may, however,be a small molecule, for example 4,4′-N,N′-dicarbazolebiphenyl (CDP=CBP)or tertiary aromatic amines, for example TCTA. In a preferred embodimentof the present invention, at least one compound of the formula I is usedas matrix material.

In a preferred embodiment, the light-emitting layer is formed from 2 to40% by weight, preferably 5 to 35% by weight, of at least one of theaforementioned emitter materials and 60 to 98% by weight, preferably 75to 95% by weight, of at least one of the aforementioned matrixmaterials—in one embodiment at least one compound of the formula I—wherethe sum total of the emitter material and of the matrix material adds upto 100% by weight.

In particularly preferred embodiment, the light-emitting layer comprisesa compound of formula I, such as, for example,

and two carbene complexes, preferably of formula

In said embodiment, the light-emitting layer is formed from 2 to 40% byweight, preferably 5 to 35% by weight, of

and 60 to 98% by weight, preferably 65 to 95% by weight, of a compoundof the formula I and

where the sum total of the carben complexes and of the compound offormula I adds up to 100% by weight.

Suitable metal complexes for use together with the compounds of theformula I as matrix material and/or hole/exciton blocker material and/orelectron/exciton blocker material and/or hole injection material and/orelectron injection material and/or hole conductor material and/orelectron conductor material, preferably as matrix material and/orhole/exciton blocker material, in OLEDs are thus, for example, alsocarbene complexes as described in WO 2005/019373 A2, WO 2006/056418 A2,WO 2005/113704, WO 2007/115970, WO 2007/115981 and WO 2008/000727.Explicit reference is made here to the disclosure of the WO applicationscited, and these disclosures shall be considered to be incorporated intothe content of the present application.

If the blocking layer for holes/excitons (4) does not comprise anycompounds of the formula I, the OLED has—if a blocking layer for holesis present—hole blocker materials typically used in OLEDs, such as2,6-bis(N-carbazolyl)pyridine (mCPy),2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (bathocuproin, (BCP)),bis(2-methyl-8-quinolinato)-4-phenylphenylato)aluminum(III) (BAlq),phenothiazine S,S-dioxide derivates and1,3,5-tris(N-phenyl-2-benzylimidazolyl)benzene) (TPBI), TPBI also beingsuitable as electron-conducting material. Further suitable hole blockersand/or electron conductor materials are2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1-H-benzimidazole),2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole,8-hydroxyquinolinolatolithium,4-(naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole,1,3-bis[2-(2,2′-bipyridin-6-yl)-1,3,4-oxadiazo-5-yl]benzene,4,7-diphenyl-1,10-phenanthroline,3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole,6,6′-bis[5-(biphenyl-4-yl)-1,3,4-oxadiazo-2-yl]-2,2′-bipyridyl,2-phenyl-9,10-di(naphthalene-2-yl)anthracene,2,7-bis[2-(2,2′-bipyridin-6-yl)-1,3,4-oxadiazo-5-yl]-9,9-dimethylfluorene,1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene,2-(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline,tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane,2,9-bis(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline,1-methyl-2-(4-(naphthalene-2-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline.In a further embodiment, it is possible to use compounds which comprisearomatic or heteroaromatic rings joined via groups comprising carbonylgroups, as disclosed in WO2006/100298, disilyl compounds selected fromthe group consisting of disilylcarbazoles, disilylbenzofurans,disilylbenzothiophenes, disilylbenzophospholes, disilylbenzothiopheneS-oxides and disilylbenzothiophene S,S-dioxides, as specified, forexample, in PCT applications PCT/EP2008/058207 and PCT/EP2008/058106,which were yet to be published at the priority date of the presentapplication, and disilyl compounds as disclosed in WO02008/034758, as ablocking layer for holes/excitons (4) or as matrix materials in thelight-emitting layer (3).

Suitable electron conductor materials for the layer (5) of the inventiveOLEDs comprise metals chelated to oxinoid compounds, such as2,2′,2″-(1,3,5-phenylene)tris[1-phenyl-1H-benzimidazole] (TPBI),tris(8-quinolinolato)aluminum (Alq₃), compounds based on phenanthroline,such as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (DDPA=BCP) or4,7-diphenyl-1,10-phenanthroline (DPA), and azole compounds such as2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole (PBD) and3-(4-biphenylyl)-4-phenyl-5-(4-t-butylphenyl)-1,2,4-triazole (TAZ),8-hydroxyquinolinolatolithium (Liq), 4,7-diphenyl-1,10-phenanthroline(BPhen), bis(2-methyl-8-quinolinolato)-4-(phenylphenolato)aluminum(BAlq), 1,3-bis[2-(2,2′-bipyridin-6-yl)-1,3,4-oxadiazo-5-yl]benzene(Bpy-OXD),6,6′-bis[5-(biphenyl-4-yl)-1,3,4-oxadiazo-2-yl]-2,2′-bipyridyl(BP-OXD-Bpy), 4-(naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole (NTAZ),2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (NBphen),2,7-bis[2-(2,2′-bipyridin-6-yl)-1,3,4-oxadiazo-5-yl]-9,9-dimethylfluorene(Bby-FOXD), 1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene(OXD-7), tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane (3TPYMB),1-methyl-2-(4-(naphthalen-2-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline(2-NPIP), 2-phenyl-9,10-di(naphthalen-2-yl)anthracene (PADN),2-(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (HNBphen). Thelayer (5) may serve both to facilitate electron transport and as abuffer layer or barrier layer in order to prevent quenching of theexciton at the interfaces of the layers of the OLED. The layer (5)preferably improves the mobility of the electrons and reduces quenchingof the exciton. In a preferred embodiment, TPBI is used as the electronconductor material. In another preferred embodiment, BCP is used as theelectron conductor material. In principle, it is possible that theelectron conductor layer comprises at least one compound of the formulaI as electron conductor material.

Among the materials mentioned above as hole conductor materials andelectron conductor materials, some may fulfil several functions. Forexample, some of the electron-conducting materials are simultaneouslyhole-blocking materials when they have a low-lying HOMO. These can beused, for example, in the blocking layer for holes/excitons (4).However, it is likewise possible that the function as a hole/excitonblocker is also adopted by the layer (5), such that the layer (4) can bedispensed with.

The charge transport layers can also be electronically doped in order toimprove the transport properties of the materials used, in order firstlyto make the layer thicknesses more generous (avoidance of pinholes/shortcircuits) and in order secondly to minimize the operating voltage of thedevice. For example, the hole conductor materials can be doped withelectron acceptors; for example, phthalocyanines or arylamines such asTPD or TDTA can be doped with tetrafluorotetracyanquinodimethane(F4-TCNQ) or with MoO₃ or WO₃. The electron conductor materials can bedoped, for example, with alkali metals, for example Alq₃ with lithium.In addition, electron conductors can be doped with salts such as Cs₂CO₃,or 8-hydroxyquinolatolithium (Liq). Electronic doping is known to thoseskilled in the art and is disclosed, for example, in W. Gao, A. Kahn, J.Appl. Phys., Vol. 94, No. 1, 1 Jul. 2003 (p-doped organic layers); A. G.Werner, F. Li, K. Harada, M. Pfeiffer, T. Fritz, K. Leo. Appl. Phys.Lett., Vol. 82, No. 25, 23 Jun. 2003 and Pfeiffer et al., OrganicElectronics 2003, 4, 89-103. For example, the hole conductor layer may,in addition to a carbene complex, e.g. Ir(dpbic)₃, be doped with MoO₃ orWO₃. For example, the electron conductor layer may comprise BCP dopedwith Cs₂CO₃.

The cathode (6) is an electrode which serves to introduce electrons ornegative charge carriers. Suitable materials for the cathode areselected from the group consisting of alkali metals of group Ia, forexample Li, Cs, alkaline earth metals of group IIa, for example calcium,barium or magnesium, metals of group IIb of the periodic table of theelements (old IUPAC version), comprising the lanthanides and actinides,for example samarium. In addition, it is also possible to use metalssuch as aluminum or indium, and combinations of all metals mentioned. Inaddition, alkali metal, especially lithium-comprising organometalliccompounds, or alkali metal fluorides, such as, for example, LiF, CsF, orKF can be applied between the organic layer and the cathode in order toreduce the operating voltage.

The OLED according to the present invention may additionally comprisefurther layers which are known to those skilled in the art. For example,a layer which facilitates the transport of the positive charge and/ormatches the band gaps of the layers to one another may be appliedbetween the layer (2) and the light-emitting layer (3). Alternatively,this further layer may serve as a protective layer. In an analogousmanner, additional layers may be present between the light-emittinglayer (3) and the layer (4) in order to facilitate the transport ofnegative charge and/or to match the band gaps between the layers to oneanother. Alternatively, this layer may serve as a protective layer.

In a preferred embodiment, the inventive OLED, in addition to layers (1)to (6), comprises at least one of the following layers mentioned below:

-   -   a hole injection layer between the anode (1) and the        hole-transporting layer (2) having a thickness of 2 to 100 nm,        preferably 5 to 50 nm;    -   a blocking layer for electrons between the hole-transporting        layer (2) and the light-emitting layer (3);    -   an electron injection layer between the electron-transporting        layer (5) and the cathode (6).

Materials for a hole injection layer may be selected from copperphthalocyanine,4,4′,4″-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA),4,4′,4″-tris(N-(2-naphthyl)-N-phenylamino)triphenylamine (2T-NATA),4,4′,4″-tris(N-(1-naphthyl)-N-phenylamino)triphenylamine (1T-NATA),4,4′,4″-tris(N,N-diphenylamino)triphenylamine (NATA), titanium oxidephthalocyanine, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane(F4-TCNQ), pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile(PPDN), N,N,N′,N′-tetrakis(4-methoxyphenyl)benzidine (MeO-TPD),2,7-bis[N,N-bis(4-methoxyphenyl)amino]-9,9-spirobifluorene(MeO-Spiro-TPD),2,2′-bis[N,N-bis(4-methoxyphenyl)amino]-9,9-spirobifluorene(2,2′-MeO-Spiro-TPD),N,N′-diphenyl-N,N′-di-[4-(N,N-ditolylamino)phenyl]benzidine (NTNPB),N,N′-diphenyl-N,N′-di-[4-(N,N-diphenylamino)phenyl]benzidine (NPNPB),N,N′-di(naphthalen-2-yl)-N,N′-diphenylbenzene-1,4-diamine (α-NPP). Inprinciple, it is possible that the hole injection layer comprises atleast one compound of the formula I as hole injection material. Inaddition, polymeric hole-injection materials can be used such aspoly(N-vinylcarbazole) (PVK), polythiophenes, polypyrrole, polyaniline,self-doping polymers, such as, for example, sulfonatedpoly(thiophene-3-[2[(2-methoxyethoxy)ethoxy]-2,5-diyl) (Plexcore® OCConducting Inks commercially available from Plextronics), and copolymerssuch as poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) alsocalled PEDOT/PSS.

As a material for the electron injection layer, LiF, for example, can beselected. In principle, it is possible that the electron injection layercomprises at least one compound of the formula I as electron injectionmaterial.

The person skilled in the art is aware (for example on the basis ofelectrochemical studies) of how suitable materials have to be selected.Suitable materials for the individual layers are known to those skilledin the art and are disclosed, for example, in WO 00/70655.

In addition, it is possible that some of the layers used in theinventive OLED have been surface-treated in order to increase theefficiency of charge carrier transport. The selection of the materialsfor each of the layers mentioned is preferably determined by obtainingan OLED with a high efficiency and lifetime.

The inventive OLED can be produced by methods known to those skilled inthe art. In general, the inventive OLED is produced by successive vapordeposition of the individual layers onto a suitable substrate. Suitablesubstrates are, for example, glass, inorganic semiconductors or polymerfilms. For vapor deposition, it is possible to use customary techniques,such as thermal evaporation, chemical vapor deposition (CVD), physicalvapor deposition (PVD) and others. In an alternative process, theorganic layers of the OLED can be applied from solutions or dispersionsin suitable solvents, employing coating techniques known to thoseskilled in the art.

In general, the different layers have the following thicknesses: anode(1) 50 to 500 nm, preferably 100 to 200 nm; hole-conducting layer (2) 5to 100 nm, preferably 20 to 80 nm, light-emitting layer (3) 1 to 100 nm,preferably 10 to 80 nm, blocking layer for holes/excitons (4) 2 to 100nm, preferably 5 to 50 nm, electron-conducting layer (5) 5 to 100 nm,preferably 20 to 80 nm, cathode (6) 20 to 1000 nm, preferably 30 to 500nm. The relative position of the recombination zone of holes andelectrons in the inventive OLED in relation to the cathode and hence theemission spectrum of the OLED can be influenced, among other factors, bythe relative thickness of each layer. This means that the thickness ofthe electron transport layer should preferably be selected such that theposition of the recombination zone is matched to the optical resonatorproperty of the diode and hence to the emission wavelength of theemitter. The ratio of the layer thicknesses of the individual layers inthe OLED depends on the materials used. The layer thicknesses of anyadditional layers used are known to those skilled in the art. It ispossible that the electron-conducting layer and/or the hole-conductinglayer have greater thicknesses than the layer thicknesses specified whenthey are electrically doped.

Use of the compounds of the formula I in at least one layer of the OLED,preferably in the light-emitting layer (preferably as a matrix material)and/or in the blocking layer for holes/excitons makes it possible toobtain OLEDs with high efficiency and with low use and operatingvoltage. Frequently, the OLEDs obtained by the use of the compounds ofthe formula I additionally have high lifetimes. The efficiency of theOLEDs can additionally be improved by optimizing the other layers of theOLEDs. For example, high-efficiency cathodes such as Ca or Ba, ifappropriate in combination with an intermediate layer of LiF, can beused. Shaped substrates and novel hole-transporting materials whichbring about a reduction in the operating voltage or an increase in thequantum efficiency are likewise usable in the inventive OLEDs. Moreover,additional layers may be present in the OLEDs in order to adjust theenergy level of the different layers and to facilitateelectroluminescence.

The OLEDs may further comprise at least one second light-emitting layer.The overall emission of the OLEDs may be composed of the emission of theat least two light-emitting layers and may also comprise white light.

The OLEDs can be used in all apparatus in which electroluminescence isuseful. Suitable devices are preferably selected from stationary andmobile visual display units and illumination units. Stationary visualdisplay units are, for example, visual display units of computers,televisions, visual display units in printers, kitchen appliances andadvertising panels, illuminations and information panels. Mobile visualdisplay units are, for example, visual display units in cellphones,tablet PCs, laptops, digital cameras, MP3 players, vehicles anddestination displays on buses and trains. Further devices in which theinventive OLEDs can be used are, for example, keyboards; items ofclothing; furniture; wallpaper.

In addition, the present invention relates to a device selected from thegroup consisting of stationary visual display units such as visualdisplay units of computers, televisions, visual display units inprinters, kitchen appliances and advertising panels, illuminations,information panels, and mobile visual display units such as visualdisplay units in cellphones, tablet PCs, laptops, digital cameras, MP3players, vehicles and destination displays on buses and trains;illumination units; keyboards; items of clothing; furniture; wallpaper,comprising at least one inventive organic light-emitting diode or atleast one inventive light-emitting layer.

The following examples are included for illustrative purposes only anddo not limit the scope of the claims. Unless otherwise stated, all partsand percentages are by weight.

EXAMPLES Example 1

a) A mixture of 5.00 g (24.1 mmol) 6H-benzimidazolo[1,2-a]benzimidazole,6.56 g (26.5 mmol) 2-bromodibenzofuran, 5.00 g (36.2 mmol) potassiumcarbonate and 920 mg (4.8 mmol) copper (I) iodide in 50 ml1-methyl-2-pyrrolidon (NMP) are stirred under argon at 200° C. for 24 h.The reaction mixture is cooled to 20° C. and 100 ml dichloromethane areadded. The reaction mixture is filtered on silica gel withdichloromethane. The organic phase is washed with water and is driedwith magnesium sulfate. The solvent is distilled off. The product isdecocted with methyl ethyl ketone (MEK) and filtered off. (yield: 2.50 g(28%)).

¹H NMR (400 MHz, DMSO-d6): δ 8.67 (s, 1H), 8.22-8.20 (m, 3H), 8.01 (s,2H), 7.80 (d, J=8.3 Hz, 1H), 7.59-7.65 (m, 3H), 7.40-7.50 (m, 3H),7.28-7.37 (m, 2H). MS (APCI(pos), m/z): 374 (M⁺¹).

b) 3.00 g (8.03 mmol)5-dibenzofuran-2-ylbenzimidazolo[1,2-a]benzimidazole is dissolved at 50°C. under argon in 15 ml DMF. 2.14 g (12.1 mmol) N-Bromosuccinimide isadded. The reaction mixture is stirred under argon at 50° C. for 18 h.The precipitated product is filtered off and is washed with DMF,ethanol, water and again ethanol (yield: 2.85 g (78%)).

¹H NMR (400 MHz, THF-d8): δ 8.56 (d, J=2.1 Hz, 1H), 8.23 (d, J=1.9 Hz,1H), 8.10-8.14 (m, 2H), 7.98 (dd, J=2.3 Hz, J=8.7 Hz, 1H), 7.83 (d,L=8.7 Hz, 1H), 7.64-7.70 (m, 2H), 7.51-7.56 (m, 2H), 7.36-7.43 (m, 4H).

c) 1.50 g (3.32 mmol)2-bromo-5-dibenzofuran-2-yl-benzimidazolo[1,2-a]benzimidazole, 1.50 g(1.59 mmol)4,4,5,5-tetramethyl-2-[3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]-1,3,2-dioxaborolane,4.02 g (16.6 mmol) potassium phosphate tribasic monohydrate, 15 mldioxane, 50 ml xylene and 10 ml water are degassed with argon. 82 mg(0.20 mmol) 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (sPhos) and7.4 mg (0.033 mmol) palladium(II) acetate are added. The reactionmixture is degassed with argon and is stirred for 22 h at 100° C. underargon. 40 ml of a 1% sodium cyanide solution are added and the reactionmixture is refluxed for 1 h, cooled to 20° C. and the product isfiltered off. The product is washed with water and ethanol and decodedin MEK (yield: 1.05 g (38.5%)).

¹H NMR (400 MHz, TFA-d1): δ 8.54 (s, 2H), 8.41 (d, J=2.3 Hz, 2H), 8.37(d, J=8.0 Hz, 2H) 8.07-8.19 (m, 6H), 7.927.95 (m, 4H), 7.68-7.88 (m,14H), 7.54 (t, J=7.5 Hz, 2H). MS (APCI(pos), m/z): 821 (M⁺¹).

Example 2

a) 19.7 g (96.5 mmol) iodo-benzene, 31.4 g (96.5 mmol) caesiumcarbonate, 2.30 g (12.1 mmol) copper(I) iodide and 2.78 g (24.1 mmol)L-proline are added to 10.0 g (48.3 mmol)5H-benzimidazo[1,2-a]benzimidazole in 150 ml DMSO under nitrogen. Thereaction mixture is stirred for 26 h at 120° C. and is filtered on Hyflowith toluene. The organic phase is washed with water and is dried withmagnesium sulfate. The solvent is removed in vacuum. The product isfiltered on silica gel with toluene and is decocted with diethyl ether(yield: 7.77 g (57%)).

¹H NMR (400 MHz, CDCl₃): δ 7.81-7.88 (m, 5H), 7.57-7.67 (m, 2H),7.45-7.50 (m, 1H), 7.31-7.40 (m, 4H)

b) The reaction is carried out according to example 1 b).

¹H NMR (400 MHz, CDCl₃): δ 8.02 (d, J=1.7 Hz, 1H), 7.83-7.87 (m, 3H),7.64-7.73 (m, 3H), 7.58-7.61 (m, 1H), 7.39-7.53 (m, 4H)

c) 1.50 g (4.14 mmol)2-bromo-5-phenyl-benzimidazolo[1,2-a]benzimidazole, 5.02 g (20.7 mmol)potassium phosphate tribasic monohydrate, 15 ml dioxane, 50 ml tolueneand 12 ml water are added to 2.23 g (4.56 mmol)9-[8-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)dibenzofuran-2-yl]carbazole.The mixture is degassed with argon. 100 mg (0.250 mmol)2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (SPhos) and 93 mg (0.042mmol) palladium(II) acetate are added. The reaction mixture is degassedwith argon and is stirred for 21 h at 100° C. under argon. 40 ml of a 1%sodium cyanide solution are added and the reaction mixture is refluxedfor 1 h. The organic phase is separated and the crystallized product isfiltered off, washed with ethanol, water and ethanol. The product iscrystallized from toluene (yield 1.52 g (60%)).

¹H NMR (400 MHz, THF-d8): δ=8.53 (d, J=1.7 Hz, 1H), 8.40 (d, J=1.7 Hz,1H), 8.37 (s, 1H), 8.20 (s, 1H), 8.17 (s, 1H), 8.11-8.14 (m, 1H),7.98-8.03 (m, 3H), 7.90 (d, J=8.5 Hz, 1H), 7.78 (d, J=8.6 Hz, 1H),7.67-7.73 (m, 4H), 7.60-7.64 (m, 2H), 7.33-7.44 (m, 4H), 7.33-7.37 (m,2H), 7.24-7.28 (m, 2H) MS (APCI(pos), m/z): 615 (M⁺¹).

Example 3

a) 7.78 g (25 mmol) 1-bromo-3-iodo-benzene, 16.3 g (50.0 mmol) caesiumcarbonate, 1.24 g (6.50 mmol) copper(I) iodide and 1.50 g (13.0 mmol)L-proline are added to 5.18 g (25.0 mmol) mmol)5H-benzimidazo[1,2-a]benzimidazole in 100 ml dimethylsulfoxide (DMSO)under nitrogen. The reaction mixture is stirred for 18 h at 100° C. andpoured into water. The organic phase is extracted with dichloromethaneand dried with magnesium sulfate. The solvent is distilled off. Columnchromatography on silica gel with toluene gives the product (yield 8.35g (92%)).

¹H NMR (400 MHz, CDCl₃): δ 8.54 (d, J=2.1 Hz, 1H), 8.37-8.40 (m, 1H),8.16-8.199 (m, 1H), 7.93-7.95 (m, 1H), 7.60-7.74 (m, 4H), 7.41-7.7.50(m, 3H). MS (APCI(pos), m/z): 444 (M⁺¹) 442 (M⁺¹), 441 (M⁺¹)

b) The reaction is carried out according to example 1 b) except that5-(3-bromophenyl)benzimidazolo[1,2-a]benzimidazole is used as startingmaterial instead of5-dibenzofuran-2-ylbenzimidazolo[1,2-a]benzimidazole.

¹H NMR (400 MHz, CDCl₃): δ 8.54 (d, J=2.1 Hz, 1H), 8.37-8.40 (m, 1H),8.16-8.199 (m, 1H), 7.93-7.95 (m, 1H), 7.60-7.74 (m, 4H), 7.41-7.7.50(m, 3H). MS (APCI(pos), m/z): 444 (M⁺¹), 442 (M⁺¹), 441 (M⁺¹).

Example 4

a) 1.00 g (3.53 mmol) 5-phenylbenzimidazolo[1,2-a]benzimidazole (example2a) and 850 mg (2.65 mmol) diacetoxy-iodobenzene in 10 ml acetic acidand 10 ml acetic acid anhydride are heated to 60° C. and then cooled to25° C. 340 mg (1.34 mmol) iodine are added. 10 drops of sulfuric acidare added and the reaction mixture is stireed under nitrogen at 25° C.for 18 h. The product is filtered off and is washed with acetic acid,ethanol, water and again ethanol. The product is decocted with methylethyl ketone (yield: 560 mg (40%)).

¹H NMR (400 MHz, THF-d8): δ=8.39 (d, J=1.6 Hz, 1H), 8.11-8.14 (m, 1H),7.97-8.00 (m, 2H), 7.61-7.71 (m, 4H), 7.37-7.48 (m, 4H). MS (APCI(pos),m/z): 444 (M⁺¹), 442 (M⁺¹), 441 (M⁺¹)

b) 750 mg (2.01 mmol) 2-iodo-5-phenyl-benzimidazolo[1,2-a]benzimidazole,1.31 g (4.02 mmol) caesium carbonate, 77 mg (0.40 mmol) copper(I) iodideand 93 mg (0.80 mmol) L-proline are added to 460 mg (221 mmol) carbazolein 10 ml dimethylsulfoxide (DMSO) under nitrogen. The reaction mixtureis stirred for 23 h at 120° C. under nitrogen, poured into water and theproduct is filtered off. Column chromatography on silica gel withtoluene, than toluene/ethyl acetate results in the product.

¹H NMR (400 MHz, THF-d8): δ=8.30 (d, J=2.0 Hz, 1H), 8.21 (d, J=7.8 Hz,2H), 8.03-8.11 (m, 3H), 7.90 (d, J=8.5 Hz, 1H), 7.67-7.91 (m, 3H),7.47-7.55 (m, 2H), 7.33-7.42 (m, 6H), 7.25-7.29 (m, 2H).

Example 5

The synthesis of9-phenyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)carbazole isdescribed in WO2012/023947A1. 1.30 g (2.87 mmol)2-bromo-5-dibenzofuran-2-yl-benzimidazolo[1,2-a]benzimidazole (example1c)), 3.21 g (14.4 mmol) potassium phosphate tribasic monohydrate, 15 mldioxane, 50 ml toluene and 10 ml water are added to 1.48 g (3.45 mmol)9-phenyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)carbazole. Themixture is degassed with argon. 71 mg (0.17 mmol)2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (SPhos) and 65 mg (0.029mmol) palladium(II) acetate are added. The reaction mixture is degassedwith argon and is stirred for 6 h at 100° C. under argon. 40 ml of a 1%sodium cyanide solution are added and the reaction mixture is refluxedfor 1 h. The water phase is extracted with dichloromethane and washedwith 20% HCl. The organic phase is dried with magnesium sulfate and thesolvent is distilled off. Column chromatography on silica gel withtoluene gives the product. MS (APCI(pos), m/z): 615 (M⁺¹).

Example 6

a) 5.00 g (17.7 mmol) 5-phenylbenzimidazolo[1,2-a]benzimidazole, 5.12 g(15.9 mmol) (diacetoxyido)benzene and 4.03 g (15.9 mmol) Iodine arestirred at 25° C. for 28 h. The reaction mixture is poured into a 10%sodium hydrosulfite solution. The product is filtered off, washed withwater and ethanol, decocted with diethyl ether, filtered off, washedwith ether and decocted with methyl ethyl ketone (MEK) (yield: 5.67 g(87%)).

b) 5.00 g (12.2 mmol) 2-iodo-5-phenyl-benzimidazolo[1,2-a]benzimidazole,2.25 g (13.4 mmol) carbazole, 2.53 g (18.3 mmol) potassium carbonate and470 mg (2.44 mmol) copper iodide in 150 ml NMP are stirred undernitrogen at 200° C. for 25 h. The solvent is distilled off.Dichloromethane is added and the organic phase is washed with water, 30%NaOH, water and a 1M solution of 1amino-1-propanol in water. The organicphase is dried with magnesium sulfate and is filtered on silica gel.Column chromatography on silica gel with toluene/ethyl acetate 100/1gives the product (yield: 4.21 g (77%)).

¹H NMR (400 MHz, THF-d8): δ=8.30 (d, J=2.0 Hz, 1H), 8.21 (d, J=7.8 Hz,2H), 8.03-8.11 (m, 3H), 7.90 (d, J=8.5 Hz, 1H), 7.67-7.91 (m, 3H),7.47-7.55 (m, 2H), 7.33-7.42 (m, 6H), 7.25-7.29 (m, 2H).

Example 7

a) 76.9 g (0.460 mol) carbazole and 104 g (0.460 mol)1-iodopyrrolidine-2,5-dione (NIS) in 100 m ml acetic acid are stirredunder nitrogen at 20° C. After 5 h the product is filtered off. Theproduct is crystalized from 900 ml ethanol using 2 g charcoal. Theethanol solution is filtered hot. The ethanol solution is cooled to 20°C. and the product is filtered off (yield: 59.5 g (44%)).

b) 19.7 g (67.0 mmol) 3-iodo-9H-carbazole and 2.95 g (73.7 mmol) sodiumhydride 60% dispersion in mineral oil in 500 ml tetrahydrofuran (THF) isstirred at 50° C. under nitrogen for 1 h. 12.8 g (67.0 mmol)4-methylbenzenesulfonyl chloride in 100 ml THF are added at 20° C. Thereaction mixture is stirred for 1 h at 20° C. and is then stirred for 1h at 50° C. The solution is filtered and the solvent is distilled off.200 ml ethyl acetate are added and the organic phase is washed with asolution of citric acid, sodium hydrogen carbonate and water. Thesolvent is partly removed until the product starts to crystalize. Theproduct is filtered off and washed with methanol (yield: 23 g (79%)).

c) 36.0 g (174 mmol) 6H-benzimidazolo[1,2-a]benzimidazole, 77.8 (174mmol) 3-iodo-9-(p-tolylsulfonyl) carbazole, 106 g (0.500 mol) potassiumphosphate, 5.5 g (28.9 mmol) copper iodide, and 111 g (0.972 mol)trans-cyclohexane-1.2-diamime in 900 ml dioxane are stirred at 100° C.48 h under nitrogen. The product is filtered off, washed with dioxane,and ethanol and is used without purification in the next reaction step.

d) A solution of 11.3 g (202 mmol) potassium hydroxide in 500 ml ethanolis added under nitrogen within 5 minutes to 53 g (101 mmol)5-[9-(p-tolylsulfonyl)carbazol-3-yl]benzimidazolo[1,2-a]benzimidazole in500 ml boiling ethanol. After 5 h the product is filtered off and iswashed with ethanol, water and methanol (yield: 32 g (85.4%)). ¹H NMR(400 MHz, DMSO-d6): δ 11.6 (s, 1H), 8.57 (d, J=7.8 Hz, 1H), 8.22-8.28(m, 3H), 7.74-7-82 (m, 2H), 7.57-7.62 (m, 2H), 7.38-7.54 (m, 4H),7.27-7.34 (m, 2H), 7.20-7.24 (m, 1H).

e) 480 mg (1.29 mmol)5-(9H-carbazol-3-yl)benzimidazolo[1,2-a]benzimidazole, 530 mg (1.29mmol) 2-iodo-5-phenyl-benzimidazolo[1,2-a]benzimidazole, 100 mg (0.525mmol) copper iodide, 1.06 g (5.00 mmol) potassium phosphate and 1.00 g(8.76 mmol) trans-cyclohexane-1.2-diamine in 10 ml dioxane are refluxedunder nitrogen for 6 h. The product is filtered off and is washed withdioxane and then methanol (yield: 440 mg (52%)). ¹H NMR (400 MHz,CDCl₃): δ 8.54 (d, J=1.9 Hz, 1H), 8.23 (d, J=7.8 Hz, 1H), 8.02-8.07 (m,2H), 7.88-7.93 (m, 4H), 7.80-7.85 (m, 3H), 7.48-7.72 (m, 9H), 7.31-7.43(m, 7H)

Example 8

1.00 g (2.44 mmol) 2-iodo-5-phenyl-benzimidazolo[1,2-a]benzimidazole,610 mg (2.93 mmol) 6H-benzimidazolo[1,2-a]benzimidazole, 93 mg (0.49mmol) copper iodide, 1.59 g (4.489 mmol) caesium carbonate and 113 mg(0.98 mmol) L-proline in 10 ml DMSO are stirred at 150° C. undernitrogen for 43 h. The reaction mixture is poured into water and theproduct is filtered off. The product is washed with water. Columnchromatography on silica gel with toluene/ethyl acetate 19/1 ant than1/1 gives the product (yield: 220 mg (18%)). ¹H NMR (400 MHz, THF-d8): δ8.59 (d, J=1.8 Hz, 1H), 8.06-8.13 (m, 1H), 8.00-8.06 (m, 4H), 7.81-7.87(m, 1H), 7.75-7.81 (m, 1H), 7.72-7.74 (m, 1H), 7.50-7.69 (m, 4H),7.43-7.49 (m, 1H), 7.31-7.42 (m, 4H), 7.24-7.30 (m, 2H). MS (APCI(pos),m/z): 489 (M⁺¹),

Example 9

1.00 g (2.76 mmol) 2-bromo-5-phenyl-benzimidazolo[1,2-a]benzimidazole,1.15 g (3.31 mmol)2-dibenzofuran-4-yl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 1.91 g(13.8 mmol) potassium carbonate, 10 ml dioxane, 30 ml xylene and 7 mlwater are degassed with argon. 23 mg (0.055 mmol)2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (sPhos) and 6.2 mg(0.028 mmol) palladium(II) acetate are added. The reaction mixture isdegassed with argon and is stirred for 21 h at 120° C. under argon. 40ml of a 1% sodium cyanide solution are added and the reaction mixture isrefluxed for 1 h. Dichloromethane is added and the organic phase isseparated. The organic phase is dried with magnesium sulfate and thesolvent is distilled off. The product is decocted in toluene, filteredoff and washed with toluene (yield: 0.91 g (73%)). ¹H NMR (400 MHz,CDCl₃): δ 8.45 (d, J=1.0 Hz, 1H), 8.04-8.07 (m, 1H), 7.99-8.00 (m, 6H),7.74-7-76 (m, 1H), 7.66-7.71 (m, 3H), 7.61-7.64 (m, 1H), 7.49-7.54 (m,3H), 7.38-7.47 (m, 3H).

Example 10

a) 4.70 g (10.8 mmol)5-(3,5-diphenylphenyl)benzimidazolo[1,2-a]benzimidazole, 3.30 g (15.9mmol) (diacetoxyido)benzne and 2.60 g (10.3 mmol) iodine are stirred at25° C. for 18 h. The reaction mixture is poured into a 10% sodiumhydrosulfite solution. The product is filtered off, washed with waterand ethanol, decocted with t-butylmethylether, filtered off and washedwith t-butylmethylether (yield: 5.64 g (98%)). ¹H NMR (400 MHz,DMSO-d6): δ 8.62 (d, J=1.6 Hz, 1H), 8.36-8.38 (m, 1H), 8.133 (s, 1H),8.129 (s, 1H), 8.01-8.02 (m, 1H), 7.87-7-89 (m, 4H), 7.75-7.78 (m, 1H),7.59-7.61 (m, 1H), 7.51-7.56 (m, 4H), 7.43-7.47 (m, 5H).

b) Example 6b) is repeated, except that instead of2-iodo-5-phenyl-benzimidazolo[1,2-a]benzimidazole the product of Example10a) is used. ¹H NMR (400 MHz, DMSO-d6): δ 8.32 (d, J=1.8 Hz, 1H), 8.29(d, J=1.6 Hz, 2H), 8.20-8.22 (m, 2H), 8.11-8.13 (m, 1H), 8.04-8.05 (m,1H), 7.85-7.95 (m, 6H), 7.52-7.57 (m, 5H), 7.36-7.47 (m, 8H), 7.25-7.30(m, 2H).

Example 11

Example 6b) is repeated, except that instead of2-dibenzofuran-4-yl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane9-phenyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)carbazole isused. ¹H NMR (400 MHz, THF-d8): δ 8.62 (d, J=1.6 Hz, 1H), 8.40 (s, 1H),8.31 (d, J=7.7 Hz, 1H), 8.20 (d, J=7.3 Hz, 1H), 8.05 (d, J=7.7, 2H),7.88 (dd, J=1.6 Hz, 8.4 Hz, 1H), 7.64-7.78 (m, 9H), 7.37-7.56 (m, 7H),7.29-7.33 (m, 1H). MS (APCI(pos), m/z): 525 (M⁺¹).

Application Example 1

The ITO substrate used as the anode is first cleaned with anacetone/isopropanol mixture in an ultrasound bath. To eliminate anypossible organic residues, the substrate is exposed to a continuousozone flow in an ozone oven for further 25 minutes. This treatment alsoimproves the hole injection properties of the ITO. Then Plexcore® OCAJ20-1000 (commercially available from Plextronics Inc.) is spin-coatedand dried to form a hole injection layer (˜40 nm).

Thereafter, the organic materials specified below are applied by vapordeposition to the clean substrate at a rate of approx. 0.5-5 nm/min atabout 10⁻⁷-10⁻⁹ mbar. As a hole transport and exciton blocker,

for preparation, see Ir complex (7) in the application WO02005/019373),is applied to the substrate with a thickness of 20 nm, wherein the first10 nm are doped with MoO_(x) (˜10%) to improve the conductivity.

Subsequently, a mixture of 10% by weight of emitter compound,

5% by weight of compound Ir(dpbic)₃ and 85% by weight of compound

is applied by vapor deposition in a thickness of 40 nm. Subsequently,material (A-43) is applied by vapour deposition with a thickness of 5 nmas blocker. Thereafter, a 20 nm thick electron transport layer isdeposited consisting of 50% by weight of

and of 50% of Liq

Finally a 2 nm KF layer serves as an electron injection layer and a 100nm-thick Al electrode completes the device.

All fabricated parts are sealed with a glass lid and a getter in aninert nitrogen atmosphere. To characterize the OLED, electroluminescencespectra are recorded at various currents and voltages. In addition, thecurrent-voltage characteristic is measured in combination with the lightoutput emitted. The light output can be converted to photometricparameters by calibration with a photometer.

Voltage @ EQE¹⁾ @ 300 nits [V] 300 nits [%] CIE Appl. Ex. 1 6.5 V 7%0.17 0.31 ¹⁾External quantum efficiency (EQE) is # of generated photonsescaped from a substance or a device/# of electrons flowing through it.

Application Example 2

The substrate treatment is accomplished as in example 1.

Thereafter, the organic materials specified below are applied by vapordeposition to the clean substrate at a rate of approx. 0.5-5 nm/min atabout 10⁻⁷-10⁻⁹ mbar. As a hole transport and exciton blocker,

for preparation, see Ir complex (7) in the application WO02005/019373),is applied to the substrate with a thickness of 20 nm, wherein the first10 nm are doped with MoO_(x) (˜10%) to improve the conductivity.Subsequently, a mixture of 10% by weight of emitter compound,

5% by weight of compound Ir(dpbic)₃ and 85% by weight of compound (A-43)is applied by vapor deposition in a thickness of 40 nm. Subsequently,material (A-43) is applied by vapour deposition with a thickness of 5 nmas blocker. Thereafter, a 20 nm thick electron transport layer isdeposited consisting of 50% by weight of compound (C-1) and of 50% ofLiq. Finally a 2 nm KF layer serves as an electron injection layer and a100 nm-thick Al electrode completes the device.

All fabricated parts are sealed with a glass lid and a getter in aninert nitrogen atmosphere. The characterization of the device isperformed as in example 1.

Voltage @ EQE¹⁾ @ 300 nits [V] 300 nits [%] CIE Appl. Ex. 2 4.05 V 11.2%0.35/0.60 ¹⁾External quantum efficiency (EQE) is # of generated photonsescaped from a substance or a device/# of electrons flowing through it.

Application Example 3

The sample preparation for PL measurements is performed at ambientconditions by solution processing. Therefore, 96% by weight of compound

and 4% by weight of compound

are dissolved in methylencloride and deposited onto a quartz substrateby doctor blading.

The PL spectrum and the PL quantum efficiency are measured using anabsolute quantum-yield measurement system “Quantaurus” (from Hamamatsu,Japan) at room temperature at an excitation wavelength of 370 nm.

PLQE [%] CIE Appl. Ex. 3 76.8% 0.15/0.24

Comparative Application Example 1

The device fabrication is done as in Application Example 1 except thatcompound (A-43) is replaced by compound

Application Example 4

The device is fabricated as in Comparative Application Example 1 exceptthat in the emissive layer compound V-1 is replaced by compound

The table below cleary demonstrates that compound A-24 leads as comparedto compound V-1 to a reduced voltage and a significantly blue shiftedcolour at comparable quantum efficiency.

Voltage @ EQE¹⁾ @ Host 300 nits [V] 300 nits [%] CIE Comp. Appl. Ex. 1V-1  5.44 13.51 0.302 Appl. Ex. 4 A-24 5.04 13.39 0.272

Application Example 5

The substrate treatment is accomplished as in Application Example 1.

Thereafter, the organic materials specified below are applied by vapordeposition to the clean substrate at a rate of approx. 0.5-5 nm/min atabout 10⁻⁷-10⁻⁹ mbar.

First a 10 nm thick hole transport layer,

is deposited onto the substrate which is doped with MoO_(x)(˜10%) toimprove the conductivity. Material

is deposited subsequently with 10 nm thickness as a blocker.

Then, a mixture of 10% by weight of emitter compound,

5% by weight of compound Ir(dpbic)₃ and 85% by weight of compound (V-1)is applied by vapor deposition in a thickness of 40 nm. Thereafter, a 20nm thick electron transport layer is deposited consisting of 50% byweight of compound (C-1) and of 50% of Liq. Finally a 2 nm KF layerserves as an electron injection layer and a 100 nm-thick Al electrodecompletes the device. All fabricated parts are sealed with a glass lidand a getter in an inert nitrogen atmosphere. The characterization ofthe device is performed as in example 1.

Comparative Application Example 2

The device is fabricated as in Application Example 5, except that theblocker A-51 is replaced by compound

(V-2; WO2011160757).

As shown in the table below, compound A-51 leads due to a better holeinjection to a reduced voltage as compared to compound V-2 and thus alsobetter quantum efficiency.

Voltage @ EQE¹⁾ @ EBL 300 nits [V] 300 nits [%] CIE Appl. Ex. 5 A-517.26 9.16 0.275 Comp. Appl Ex. 2 V-2  8.05 8.10 0.276

The invention claimed is:
 1. A compound of the formula

wherein R¹, R², R³, R⁴, R⁵, R⁶ and R⁷ are independently selected fromthe group consisting of H; a C₁-C₂₅ alkyl group, which can optionally besubstituted by E and/or interrupted by D; a C₆-C₂₄ aryl group, which canoptionally be substituted by G; and a C₂-C₃₀ heteroaryl group, which canoptionally be substituted by G; X¹ is a group of formula-(A¹)_(o)-(A²)_(p)-(A³)_(q)-(A⁴)_(r)—R^(16′), o is 0 or 1, p is 0 or 1,q is 0 or 1, r is 0 or 1, A¹, A², A³ and A⁴ are independently selectedfrom the group consisting of a C₆-C₂₄ arylene group, which canoptionally be substituted by G, and a C₂-C₃₀ heteroarylene group, whichcan optionally be substituted by G; wherein the groups A¹, A², A³ and A⁴may be interrupted by a group —(SiR¹⁷R¹⁸)—; X² is a group of formula-(A⁵)_(v)-(A⁶)_(s)-(A⁷)_(t)-(A⁸)_(u)—R¹⁵, —NR¹⁰R¹¹, orSi(R¹²)(R¹³)(R¹⁴), v is 0 or 1, s is 0 or 1, t is 0 or 1, u is 0 or 1,A⁵, A⁶, A⁷ and A⁸ are independently selected from the group consistingof a C₆-C₂₄ arylene group, which can optionally be substituted by G, anda C₂-C₃₀ heteroarylene group, which can optionally be substituted by G;wherein the groups A⁵, A⁶, A⁷ and A⁸ may be interrupted by a group—(SiR¹⁷R¹⁸)—; R¹⁰ and R¹¹ are independently selected from the groupconsisting of a C₆-C₂₄ aryl group, which can optionally be substitutedby G; and a C₂-C₃₀ heteroaryl group, which can optionally be substitutedby G; or R¹⁰ and R¹¹ together with the nitrogen atom to which they arebonded form a heteroaromatic ring, or ring system; R¹², R¹³ and R¹⁴ areindependently selected from the group consisting of a C₁-C₂₅alkyl group,which can optionally be substituted by E and/or interrupted by D;C₆-C₂₄aryl group, which can optionally be substituted by G; and aC₂-C₃₀heteroaryl group, which can optionally be substituted by G; R¹⁵ isa C₆-C₂₄aryl group, which can optionally be substituted by G; or aC₂-C₃₀ heteroaryl group, which can optionally be substituted by G;R^(16′) is a C₆-C₂₄aryl group, which can optionally be substituted by G;or a C₂-C₃₀ heteroaryl group, which can optionally be substituted by G;R¹⁷ and R¹⁸ are independently selected from the group consisting of aC₁-C₂₅ alkyl group, and a C₆-C₂₄aryl group, which can optionally besubstituted by a C₁-C₂₅ alkyl group; D is —CO—, —COO—, —S—, —SO—, —SO₂—,—O—, —NR⁶⁵—, —SiR⁷⁰R⁷¹—, —POR⁷²—, —CR⁶³═CR⁶⁴—, or —C≡C—, E is —OR⁶⁹,—SR⁶⁹, —NR⁶⁵R⁶⁶, —COR⁶⁸, —COOR⁶⁷, —CONR⁶⁵R⁶⁶, or halogen, G is E; aC₁-C₁₈ alkyl group; a C₆-C₂₄ aryl group; a C₆-C₂₄ aryl group, which issubstituted by F, C₁-C₁₈ alkyl, or C₁-C₁₈ alkyl which is interrupted byO; a C₂-C₃₀ heteroaryl group; or a C₂-C₃₀ heteroaryl group, which issubstituted by F, C₁-C₁₈ alkyl, or C₁-C₁₈ alkyl which is interrupted byO; R⁶³ and R⁶⁴ are independently selected from the group consisting ofH, C₆-C₁₈ aryl; C₆-C₁₈ aryl which is substituted by C₁-C₁₈ alkyl orC₁-C₁₈ alkoxy; C₁-C₁₈ alkyl; and C₁-C₁₈ alkyl which is interrupted by—O—; R⁶⁵ and R⁶⁶ are independently selected from the group consisting ofa C₆-C₁₈ aryl group; a C₆-C₁₈ aryl which is substituted by C₁-C₁₈ alkylor C₁-C₁₈ alkoxy; a C₁-C₁₈ alkyl group; and a C₁-C₁₈ alkyl group, whichis interrupted by —O—; or R⁶⁵ and R⁶⁶ together form a five or sixmembered ring, R⁶⁷ is a C₆-C₁₈ aryl group; a C₆-C₁₈ aryl group, which issubstituted by C₁-C₁₈ alkyl or C₁-C₁₈ alkoxy; a C₁-C₁₈ alkyl group; or aC₁-C₁₈ alkyl group, which is interrupted by —O—, R⁶⁸ is H; a C₆-C₁₈ arylgroup; a C₆-C₁₈ aryl group, which is substituted by C₁-C₁₈ alkyl orC₁-C₁₈ alkoxy; a C₁-C₁₈ alkyl group; or a C₁-C₁₈ alkyl group, which isinterrupted by —O—, R⁶⁹ is a C₆-C₁₈ aryl; a C₆-C₁₈ aryl, which issubstituted by C₁-C₁₈ alkyl or C₁-C₁₈ alkoxy; a C₁-C₁₈ alkyl group; or aC₁-C₁₈ alkyl group, which is interrupted by —O—, R⁷⁰ and R⁷¹ areindependently selected from the group consisting of a C₁-C₁₈ alkylgroup, a C₆-C₁₈ aryl group, and a C₆-C₁₈ aryl group, which issubstituted by C₁-C₁₈ alkyl, and R⁷² is a C₁-C₁₈ alkyl group, a C₆-C₁₈aryl group, or a C₆-C₁₈ aryl group, which is substituted by C₁-C₁₈alkyl; wherein at least one of the following conditions (i)-(v) is true:(i) when v is 0, s is 0, t is 0, and u is 0, then R⁶ is notunsubstituted phenyl; (ii) when v is 0, s is 0, t is 0, and u is 0, thenR¹⁵ is not unsubstituted phenyl; (iii) R² is not unsubstituted phenyl;(iv) R⁶ is not unsubstituted phenyl; and (v) both conditions (iii) and(iv).
 2. The compound according to claim 1, which is a compound of theformula

wherein X¹ and X² are as defined in claim
 1. 3. The compound accordingto claim 1, wherein X¹ is a group of the formula-A¹-(A²)_(p)-(A³)_(q)-(A⁴)_(r)—R¹⁶ or-(A¹)_(o)-(A²)_(p)-(A³)_(q)-(A⁴)_(r)—R^(16′), o is 0 or 1, p is 0 or 1,q is 0 or 1, r is 0 or 1, A¹, A², A³ and A⁴ are independently selectedfrom the group consisting of

R¹⁶ is a s group of the formula

R^(16′) is a group of the formula

R²¹ and R^(21′) are independently selected from the group consisting ofH, a phenyl group, and a C₁-C₁₈ alkyl group; R²² and R²³ areindependently selected from the group consisting of H,

X is O, S, or NR²⁴, and R²⁴ is a C₆-C₂₄ aryl group, or a C₂-C₃oheteroaryl group, which can optionally be substituted by G, wherein G isas defined in claim
 1. 4. The compound according to claim 1, wherein X¹is a group of the formula -A¹-(A²)_(p)-(A³)_(q)-(A⁴)_(r)—R¹⁶, or-(A¹)_(o)-(A²)_(p)-(A³)_(q)-(A⁴)_(r)—R^(16′), o is 0 or 1, p is 0 or 1,q is 0 or 1, r is 0 or 1, A¹, A², A³ and A⁴ are independently selectedfrom the group consisting of

R¹⁶ is a group of the formula

R^(16′) is a group of the formula

 and R²¹ is a group of the formula


5. The compound according to claim 1, wherein X¹ is


6. The compound according to claim 1, wherein X² is a group of formula-(A⁵)_(v)-(A⁶)_(s)-(A⁷)_(t)-(A⁸)_(u)—R¹⁵, v is 0 or 1, s is 0 or 1, t is0 or 1, u is 0 or 1, A⁵, A⁶, A⁷ and A⁸ are independently selected fromthe group consisting of

R¹⁵ is a group of the formula

R²⁶, R²⁷, R²⁹ and R³² are independently selected from the groupconsisting of H,

R³⁰ and R³³ are independently selected from the group consisting of

 and R³¹ is


7. The compound according to claim 1, wherein X² is a group of formula-(A⁵)_(v)-(A⁶)_(s)-(A⁷)_(t)-(A⁸)_(u)—R¹⁵, v is 0 or 1, s is 0 or 1, t is0 or 1, u is 0 or 1, A⁵, A⁶, A⁷ and A⁸ are independently selected fromthe group consisting of

R¹⁵ is a group of the formula


8. The compound according to claim 1, wherein X² is


9. The compound according to claim 1, which is a following compound:

Cpd. X¹ X² A-1

A-2

A-3

A-4

A-5

A-6

A-7

A-8

A-9

A-10

A-11

A-12

A-13

A-14

A-15

A-16

A-17

A-18

A-19

A-20

A-21

A-22

A-23

A-24

A-25

A-26

A-27

A-28

A-29

A-30

A-31

A-32

A-33

A-34

A-35

A-36

A-37

A-38

A-39

A-40

A-41

A-42

A-43

A-44

A-45

A-46

A-47

A-48

A-49

A-50

A-51


10. An electronic device, comprising a compound according to claim 1.11. The electronic device according to claim 10, which is anelectroluminescent device.
 12. A hole transport layer, anelectron/exciton blocking layer, or an emitting layer comprising acompound according to claim
 1. 13. An emitting layer, comprising acompound according to claim 1 as host material in combination with aphosphorescent emitter.
 14. An apparatus selected from the groupconsisting of a stationary visual display unit; a mobile visual displayunit; an illumination unit; a keyboard; an item of clothing; furniture;and wallpaper, comprising the electronic device according to claim 10.15. An electrophotographic photoreceptor, a photoelectric converter, anorganic solar cell, a switching element, an organic light emitting fieldeffect transistor, an image sensor, a dye laser and anelectroluminescent device, comprising the compound of formula Iaccording to claim 1.